Light — Paper 3 · IGCSE Physics 0625

6 Fig. 6.1 shows white light incident at P on a glass prism. Only the refracted red ray PQ is For shown in the prism. Examiner’s Use P red ray Q light white screen Fig. 6.1 (a) On Fig. 6.1, draw rays to complete the path of the red ray and the whole path of the violet ray up to the point where they hit the screen. Label the violet ray. [3] (b) The angle of incidence of the white light is increased to 40°. The refractive index of the glass for the red light is 1.52. Calculate the angle of refraction at P for the red light. angle of refraction = … [3] (c) State the approximate speed of (i) the white light incident at P, speed = … [1] (ii) the red light after it leaves the prism at Q. speed = … [1]

8 marks

Mark scheme: 6 (a) red ray refracted away from normal B1 violet ray refracted more than red ray in prism B1 violet ray further refracted from red ray to screen B1 3 (b) 1.52 = sin 40o/sin r M1 sin r = sin 40o/ 1.52 ( = 0.423) C1 r = 25o A1 3 (c) (i) 3 x 108 m/s A1 (ii) same as (i) A1 2 [8]

This question in 0625/31 May/June 2006

6 Fig. 6.1 shows a ray of light, from the top of an object PQ, passing through two glass For prisms. Examiner’s Use P A B Q C D F E Fig. 6.1 (a) Complete the path through the two prisms of the ray shown leaving Q. [1] (b) A person looking into the lower prism, at the position indicated by the eye symbol, sees an image of PQ. State the properties of this image. … [2] (c) Explain why there is no change in direction of the ray from P at points A, C, D and F. … … [1] (d) The speed of light as it travels from P to A is 3 × 108 m/s and the refractive index of the prism glass is 1.5. Calculate the speed of light in the prism. speed = … [2] (e) Explain why the ray AB reflects through 90° at B and does not pass out of the prism at B. … … … [2]

8 marks

Mark scheme: 6 (a) completed path B1 [1] (b) any two correct, -1 each incorrect virtual, inverted, same size as object B2 [2] (c) angle of incidence zero/at right angles/along normal B1 [1] (d) 1.5 = Va/Vg = 3x 108/Vg C1 Vg = 2 x 108 m/s A1 [2] (e) angle of incidence = 45°, so angle of reflection = 45°, so ray turns through 90° OR angle i> angle c B1 so totally internally reflects B1 [2] [Total: 8]

This question in 0625/31 Oct/Nov 2006

6 Fig. 6.1 shows a rectangular glass block ABCD. F 60 o A B E D C Fig. 6.1 (a) The ray FE is partly reflected and partly refracted at E. (i) On Fig. 6.1, draw in the approximate path of the refracted ray, within and beyond the block. Label the ray refracted ray. [1] (ii) On Fig. 6.1, draw in the path of the reflected ray. Label the ray reflected ray. [1] (b) A second ray, almost parallel to AE, strikes the block at E and is partly refracted at an angle of refraction of 43°. (i) State an approximate value for the angle of incidence at E. … [1] (ii) State an approximate value for the critical angle for the light in the glass block. … [1] (iii) Calculate an approximate value for the refractive index of the glass of the block. refractive index = … [2] (c) The speed of the light along ray FE is 3.0 x 108 m/s. Calculate the speed of the refracted light in the glass block. speed = … [2] [Total: 8]

8 marks

Mark scheme: 6 (a) (i) refracted ray, angle < i, emergent ray approx parallel to incident B1 (ii) reflected ray at equal angle to incident, by eye B1 [2] (b) (i) 88–90° B1 [1] (ii) 43° c.a.o. B1 [1] (iii) n = sin (his90°)/sin (his43°) C1 1.466 or 1.47 or 1.5 c.a.o. any no s.f. ğ 2 A1 [2] (c) n or his 1.5 = speed in air/speed in glass e.c.f. C1 speed in glass = 2(.0) × 108 m/s e.c.f. any no s.f. ğ 2 A1 [2] [Total: 8] IGCSE – May/June 2007 0625 03

This question in 0625/31 May/June 2007

6 Virtual images may be formed by both plane mirrors and by convex lenses. Fig. 6.1 shows a plane mirror and a convex lens. O P F F Fig. 6.1 (a) On Fig. 6.1, draw rays to locate the approximate positions of the images of the tops of the two arrow objects O and P. Label the images. [5] (b) Both images are virtual. (i) What is meant by a virtual image? … [1] (ii) State one other similarity between the two images. … [1] (iii) State one difference between the two images. … [1] [Total: 8]

8 marks

Mark scheme: 6 (a) mirror: 2 reflected rays approx correct M1 projected back to approx correct labelled image A1 note: images may be dots or lines lens: ray through F, correct by eye M1 ray through centre OR ray through other F, correct by eye M1 projected back to approx correct (labelled) image A1 (b) (i) not produced by real rays crossing OR cannot be caught on a screen OR rays appear to come from image B1 (ii) upright/right way up/erect c.a.o. B1 (iii) lens image enlarged AND mirror image same size c.a.o. OR (different) size OR (different) distance OR different side B1 [Total: 8]

This question in 0625/31 Oct/Nov 2007

8 In an optics lesson, a Physics student traces the paths of three rays of light near the boundary For between medium A and air. The student uses a protractor to measure the various angles. Examiner’s Use Fig. 8.1 illustrates the three measurements. air 0 0 180 180 medium 170 10 170 10 A 160 20 160 20 30 150 150 30 40 140 140 50 130 40 130 60 120 50 120 70 80 100110 60 110 90 70 100 80 ray 1 air 0 0 180 180 medium 170 10 170 10 A 160 20 160 20 30 150 150 30 40 140 140 50 130 40 130 60 120 50 120 70 80 100110 60 110 90 70 100 80 ray 2 air 0 0 180 180 medium 170 10 170 10 A 160 20 160 20 30 150 150 30 40 140 ray 140 50 130 40 3 130 60 120 50 120 70 80 100110 60 110 90 70 100 80 Fig. 8.1 (a) State which is the optically denser medium, A or air, and how you can tell this. For Examiner’s … Use … [1] (b) State in which medium the light travels the faster, and how you know this. … … [1] (c) State the critical angle of medium A. … [1] (d) State the full name for what is happening to ray 3. … [1] (e) The refractive index of medium A is 1.49. Calculate the value of the angle of refraction of ray 1, showing all your working. angle of refraction = … [2] (f) The speed of light in air is 3.0 × 108 m / s. Calculate the speed of light in medium A, showing all your working. speed of light = … [2] [Total: 8]

8 marks

Mark scheme: 8 (a) medium A because angle in air is bigger OR angle in A is smaller OR refracts / bends away from normal / angle of refraction greater than angle of incidence / total internal reflection only occurs in denser medium B1 (b) air: light travels faster in less dense medium OR air: air is less dense / rarer B1 (c) 42°–43° B1 (d) total internal reflection B1 (e) n = sin i / sin r OR n = sin r / sin i OR 1.49 = sin i / sin 35 C1 (allow 1.49 or refractive index instead of n in any of above) 58.719° to at least 2 s.f. Allow 58.71° A1 (f) n = speed in air / speed in medium in any arrangement OR 1.49 = 3.0 × 108 / speed in medium A C1 2.01343 × 108 m/s to at least 2 s.f. A1 [8]

This question in 0625/31 May/June 2009

8 Fig. 8.1 shows a thin converging lens. The two principal foci are shown. For Examiner’s Use principal axis F2 F1 Fig. 8.1 A vertical object, 2 cm tall, is to be positioned to the left of the lens, with one end on the principal axis. On Fig. 8.1, (a) draw the object in a position which will produce a virtual image, labelling the object with the letter O, [1] (b) draw two rays showing how the virtual image is formed, [2] (c) draw in the image, labelling it with the letter I. [1] [Total: 4]

4 marks

Mark scheme: 8 (a) 2 cm (by eye) vertical object somewhere between F2 and lens (condone no O, if clear) B1 (b) any two standard rays correctly drawn (no extrapolation needed) B1 correct rays extrapolated back to intersect B1 virtual image drawn at candidate’s intersection of extrapolated rays (condone no I, if clear) B1 [4] IGCSE – October/November 2009 0625 31

This question in 0625/31 Oct/Nov 2009

8 Fig. 8.1 shows a thin converging lens. The two principal foci are shown. For Examiner’s Use principal axis F2 F1 Fig. 8.1 A vertical object, 2 cm tall, is to be positioned to the left of the lens, with one end on the principal axis. On Fig. 8.1, (a) draw the object in a position which will produce a virtual image, labelling the object with the letter O, [1] (b) draw two rays showing how the virtual image is formed, [2] (c) draw in the image, labelling it with the letter I. [1] [Total: 4]

4 marks

Mark scheme: 8 (a) 2 cm (by eye) vertical object somewhere between F2 and lens (condone no O, if clear) B1 (b) any two standard rays correctly drawn (no extrapolation needed) B1 correct rays extrapolated back to intersect B1 virtual image drawn at candidate’s intersection of extrapolated rays (condone no I, if clear) B1 [4]

This question in 0625/32 Oct/Nov 2009

7 During a thunderstorm, thunder and lightning are produced at the same time. For Examiner’s (a) A person is some distance away from the storm. Use Explain why the person sees the lightning before hearing the thunder. … … … [1] (b) A scientist in a laboratory made the following measurements during a thunderstorm. time from start of storm / minutes 0.0 2.0 4.0 6.0 8.0 10.0 time between seeing lightning and hearing thunder / s 3.6 2.4 1.6 2.4 3.5 4.4 Fig. 7.1 (i) How many minutes after the storm started did it reach its closest point to the laboratory? … [1] (ii) How can you tell that the storm was never immediately over the laboratory? … [1] (iii) When the storm started, it was immediately above a village 1200 m from the laboratory. Using this information and information from Fig. 7.1, calculate the speed of sound. speed of sound = … [2] (iv) State the assumption you made when you calculated your answer to (b)(iii). … [1] (c) Some waves are longitudinal; some waves are transverse. For Examiner’s Some waves are electromagnetic; some waves are mechanical. Use Put ticks (✓) in the table below to indicate which of these descriptions apply to the light waves of the lightning and the sound waves of the thunder. light waves sound waves longitudinal transverse electromagnetic mechanical [3] [Total: 9]

9 marks

Mark scheme: 7 (a) idea of light travelling (much) faster than sound B1 (b) (i) 4.0 (min) B1 (ii) always a (measurable) time difference / never zero time difference Ignore time would be less B1 (iii) distance/time in any form, symbols, words, numbers OR 1200/3.6 C1 333.3 m/s to 2 or more sig figs A1 (iv) idea of light travelling instantaneously OR no wind OR idea of lightning at ground level OR no obstruction to sound Ignore echoes B1 (c) light waves sound waves longitudinal ✓ transverse ✓ electromagnetic ✓ mechanical ✓ –1 e.e.o.o. i.e. 1 mark subtracted from 3 for each error or omission B3 [9] IGCSE – May/June 2010 0625 31

This question in 0625/31 May/June 2010

6 A ray of monochromatic light passes through the glass prism shown in Fig. 6.1. For Examiner’s Use 90° 45° ray A B 61° 45° glass air C Fig. 6.1 (a) State what is meant by the term monochromatic. … … [1] (b) State the name given to what happens to the ray at A. … [1] (c) Use the values on the diagram to calculate the angle of refraction at A (The angles in a triangle add up to 180°). angle of refraction = … [1] (d) Calculate the refractive index of the glass. refractive index = … [3] (e) Explain why the ray does not emerge into the air at B, but does emerge at C. For Examiner’s … Use … … … [2] (f) An identical prism is stuck to the first prism using a transparent adhesive with the same refractive index as the glass. This is shown in Fig. 6.2. glass ray A B glass air Fig. 6.2 On Fig. 6.2, draw the path of the ray after it has reached B and until it has passed into the air again. [3] [Total: 11]

11 marks

Mark scheme: 6 (a) single wavelength/frequency accept single colour B1 (b) refraction B1 (c) 29° unit needed B1 (d) n = sini / sinr in any form OR n = sinr / sin i in any form OR sini / sinr C1 sin 45 / sin 29 OR sin 29 / sin 45 e.c.f.from (c) C1 1.458524649 to at least 2 sig figs c.a.o. accept incorrect rounding of answer to more than 3 S.F. e.g. do not accept 1.4 or 1.45 do accept 1.46 or 1.5 or 1.458 A1 (e) (at B) greater than critical angle OR ray is totally internally reflected B1 less than critical angle at C B1 (f) AB continued straight by eye, to RH glass surface, drawn with ruler B1 refracted up at RH surface C1 horizontal A1 [11] IGCSE – May/June 2010 0625 32

This question in 0625/32 May/June 2010

6 A ray of monochromatic light passes through the glass prism shown in Fig. 6.1. For Examiner’s Use 90° 45° ray A B 61° 45° glass air C Fig. 6.1 (a) State what is meant by the term monochromatic. … … [1] (b) State the name given to what happens to the ray at A. … [1] (c) Use the values on the diagram to calculate the angle of refraction at A (The angles in a triangle add up to 180°). angle of refraction = … [1] (d) Calculate the refractive index of the glass. refractive index = … [3] (e) Explain why the ray does not emerge into the air at B, but does emerge at C. For Examiner’s … Use … … … [2] (f) An identical prism is stuck to the first prism using a transparent adhesive with the same refractive index as the glass. This is shown in Fig. 6.2. glass ray A B glass air Fig. 6.2 On Fig. 6.2, draw the path of the ray after it has reached B and until it has passed into the air again. [3] [Total: 11]

11 marks

Mark scheme: 6 (a) single wavelength/frequency accept single colour B1 (b) refraction B1 (c) 29° unit needed B1 (d) n = sini / sinr in any form OR n = sinr / sin i in any form OR sini / sinr C1 sin 45 / sin 29 OR sin 29 / sin 45 e.c.f.from (c) C1 1.458524649 to at least 2 sig figs c.a.o. accept incorrect rounding of answer to more than 3 S.F. e.g. do not accept 1.4 or 1.45 do accept 1.46 or 1.5 or 1.458 A1 (e) (at B) greater than critical angle OR ray is totally internally reflected B1 less than critical angle at C B1 (f) AB continued straight by eye, to RH glass surface, drawn with ruler B1 refracted up at RH surface C1 horizontal A1 [11] IGCSE – May/June 2010 0625 33

This question in 0625/33 May/June 2010

6 Fig. 6.1 shows part of the path of a ray of light PQ travelling in an optical fibre. Q glass P R Fig. 6.1 PQ undergoes total internal reflection at Q. (a) Explain what is meant by total internal reflection, and state the conditions under which it occurs. … … … … … [3] (b) Carefully complete the path of the ray of light, until it reaches the end R of the optical fibre. [2] [Total: 5]

5 marks

Mark scheme: 6 (a) incident ray in (more) dense medium ) angle of incidence greater than critical angle/42° ) any 3 B1 × 3 no light refracted ) reflected with i = r ) (b) reflection at Q only, no further reflections B2 (allow B1 only, if there is one further reflection at lower surface) (give B0 for more than one further reflection) [Total: 5] IGCSE – October/November 2010 0625 31

This question in 0625/31 Oct/Nov 2010

9 Fig. 9.1 shows three rays of light, parallel to the axis of a thin converging lens. The rays strike the first surface of the lens. F1 and F2 are the two principal foci of the lens. F2 F1 Fig. 9.1 (a) Describe and explain what happens to the top ray as it enters the lens. … … … … … … [3] (b) On Fig. 9.1, use a ruler to, (i) complete the three rays through the lens, until they reach about 5 cm to the right of the lens, [2] (ii) draw a fourth ray, parallel to the others on the left of the lens, which passes through F2, until it reaches about 5 cm to the right of the lens. [1] (c) A lens such as that shown in Fig. 9.1 can be used as a magnifying glass. (i) On Fig. 9.1, show with an X where the object could be positioned for the lens to be used as a magnifying glass. [1] (ii) State 3 characteristics of the image formed by a magnifying glass. 1. … 2. … 3. … [2] [Total: 9]

9 marks

Mark scheme: 9 (a) refracts/bends/changes direction NOT curves Ignore converges/reflection ) downwards/inwards/towards F1/focal point/normal ) speed change/reduces on entering glass OR change of n ) any 3 B1 × 3 OR change of density ) idea of meets surface at an angle/one part of wave hits surface first ) splits into colours ) (b) (i) all 3 rays through F1 M1 all refractions correct and either all at lens centre line or all at both surfaces A1 (ii) straight line through F1 and F2 B1 (c) (i) X between vertical line through F1 and vertical line through F2 B1 (ii) virtual ) upright ) enlarged ) any 3 B2 same side (of lens as object) ) - 1 e.e.o.o. further from lens (than object) ) [Total: 9] IGCSE – October/November 2010 0625 32

This question in 0625/32 Oct/Nov 2010

9 In Fig. 9.1, a ray of light TRS is shown entering, passing through and leaving a semicircular glass block. S R U glass air T Fig. 9.1 (a) As the light enters the block, its frequency remains constant. State what happens to (i) the speed of the light as it enters the block, … (ii) the wavelength of the light as it enters the block. … [2] (b) The refractive index of the glass is 1.48. The speed of light in air is 3.00 × 108 m / s. Calculate the speed of the light in the glass. State the equation you use. speed = … [2] (c) Another ray of light enters the block along UR. On Fig. 9.1, draw a line to show what happens to this ray after it has reached R. [2] [Total: 6]

6 marks

Mark scheme: 9 (a) (i) reduced B1 (ii) reduced B1 speed in air/vacuum (b) n = in any form B1 speed in medium/gla ss 2.0/2.03 x 108 m/s B1 (c) reflection shown M1 angle correct, by eye A1 [Total: 6]

This question in 0625/33 Oct/Nov 2010

7 (a) The speed of light in air is known to be 3.0 × 108 m / s. Outline how you would use a refraction experiment to deduce the speed of light in glass. You may draw a diagram if it helps to clarify your answer. … … … … … … [4] (b) A tsunami is a giant water wave. It may be caused by an earthquake below the ocean. Waves from a certain tsunami have a wavelength of 1.9 × 105 m and a speed of 240 m / s. (i) Calculate the frequency of the tsunami waves. frequency = … [2] (ii) The shock wave from the earthquake travels at 2.5 × 103 m / s. The centre of the earthquake is 6.0 × 105 m from the coast of a country. Calculate how much warning of the arrival of the tsunami at the coast is given by the earth tremor felt at the coast. warning time = … [4] [Total: 10]

10 marks

Mark scheme: 7 (a) idea of fine ray/beam shone into (glass) block / pins appropriately placed shown in diagram or described B1 angles i & r or C measured OR correct i & r or C marked on diagram B1 sini/sinr OR sinr/sini OR 1/sinC OR sinC B1 n = speed in air/speed in glass OR c/v = sini/sinr OR n = 1/sinC OR c/v = 1/sinC B1 (b) (i) v = fλ OR 240/1.9 × 105 OR T=d/s AND f=1/T B1 0.00126 Hz OR 0.0013 Hz NOT 0.0012 Hz ignore more than 3 s.f. accept s-1 A1 (ii) distance = speed × time in any form accept s = 2d/t C1 (time for tremor =) 240 (s) or 4 mins also gives first C1 C1 (time for tsunami = ) 2500 (s) or 41 mins 40 s also gives first C1 C1 (warning time = ) 2260 (s) or 37 mins 40 s A1 [10]

This question in 0625/31 May/June 2011

8 (a) Fig. 8.1 shows a section of an optical fibre. It consists of a fibre of denser transparent material, coated with a layer of a less dense transparent material. less dense material ray denser material Fig. 8.1 One ray within the fibre has been started for you on Fig. 8.1. (i) State and explain what happens to the ray already drawn, after it reaches the boundary between the materials. … … … [2] (ii) On Fig. 8.1, carefully continue the ray until it reaches the end of the section of optical fibre. [1] (b) Fibre-optic cables are sometimes used to carry out internal examinations on the human stomach. (i) Suggest one reason why the cable is made of thousands of very thin optical fibres. … … … [1] (ii) Describe briefly how the inside of the stomach is illuminated. … … … [1] (iii) Describe briefly how the light from the stomach is transferred to the detecting equipment outside the body. … … … [1] [Total: 6]

6 marks

Mark scheme: 8 (a) (i) total (internal) reflection OR reflection but no refraction/doesn’t emerge B1 angle (of incidence} > critical angle B1 (ii) initial reflection + 0 or 1 further reflection only, not at lower surface must be straight and reach within 1cm of end B1 (b) (i) bends easily/less likely to break (ignore stronger) OR smaller pixels/ more detail/greater resolution/see smaller objects/wider field of view B1 (ii) light travels down/along/through fibres B1 (iii) light/image returns up/along/through fibres ignore cameras B1 [6]

This question in 0625/31 May/June 2011

7 (a) What is meant by the focal length of a converging lens? … … [1] (b) An object is placed in front of a converging lens. A real image is formed, as shown in Fig. 7.1. The converging lens is not shown. A object image B Fig. 7.1 (i) Explain what is meant by a real image. … [1] (ii) Rays of light from point A on the object form point B on the image. On Fig. 6.1, draw 1. a ray to find the position of the converging lens, showing the lens as a vertical straight line in this position, 2. a ray to find the position of a principal focus of the lens, marking this position F, 3. a third possible ray from A to B. [3] (iii) The distance between the object and the lens is increased. State any changes which take place in 1. the distance of the image from the lens, … 2. the size of the image. … [2] [Total: 7]

7 marks

Mark scheme: 7 (a) distance from (principal) focus/focal point to (the centre of) the lens B1 (b) (i) image can be formed on a screen OR is formed by rays of light meeting OR is formed on the opposite side of the lens from the object B1 (ii) 1. straight line ray from point A to point B AND lens at intersection of ray and axis. B1 2. ray from A parallel to axis, bent at lens to pass through B. F at intersection of ray and axis. OR Ray from point A through nearer focus, labelled F, to lens, bent at lens, then parallel to axis, to point B B1 3. any third ray from A to B, bent at lens B1 (iii) (distance from image to lens is) reduced B1 (image is) smaller B1 [7] IGCSE – May/June 2011 0625 32

This question in 0625/32 May/June 2011

7 (a) What is meant by the focal length of a converging lens? … … [1] (b) An object is placed in front of a converging lens. A real image is formed, as shown in Fig. 7.1. The converging lens is not shown. A object image B Fig. 7.1 (i) Explain what is meant by a real image. … [1] (ii) Rays of light from point A on the object form point B on the image. On Fig. 6.1, draw 1. a ray to find the position of the converging lens, showing the lens as a vertical straight line in this position, 2. a ray to find the position of a principal focus of the lens, marking this position F, 3. a third possible ray from A to B. [3] (iii) The distance between the object and the lens is increased. State any changes which take place in 1. the distance of the image from the lens, … 2. the size of the image. … [2] [Total: 7]

7 marks

Mark scheme: 7 (a) distance from (principal) focus/focal point to (the centre of) the lens B1 (b) (i) image can be formed on a screen OR is formed by rays of light meeting OR is formed on the opposite side of the lens from the object B1 (ii) 1. straight line ray from point A to point B AND lens at intersection of ray and axis. B1 2. ray from A parallel to axis, bent at lens to pass through B. F at intersection of ray and axis. OR Ray from point A through nearer focus, labelled F, to lens, bent at lens, then parallel to axis, to point B B1 3. any third ray from A to B, bent at lens B1 (iii) (distance from image to lens is) reduced B1 (image is) smaller B1 [7] IGCSE – May/June 2011 0625 33

This question in 0625/33 May/June 2011

7 (a) Fig. 7.1 shows a ray of monochromatic red light, in air, incident on a glass block at an angle of incidence of 50°. 50° Fig. 7.1 (i) State what is meant by monochromatic light. … [1] (ii) For this red ray the refractive index of the glass is 1.52. Calculate the angle of refraction for the ray. angle of refraction = … [2] (iii) Without measuring angles, use a ruler to draw the approximate path of the ray in the glass block and emerging from the block. [2] (b) The red ray in Fig. 7.1 is replaced by a ray of monochromatic violet light. For this violet ray the refractive index of the glass is 1.54. The speed of light in air is 3.00 × 108 m / s. (i) Calculate the speed of the violet light in the glass block. speed = … [2] (ii) Use a ruler to draw the approximate path of this violet ray in the glass block and emerging from the block. Make sure this path is separated from the path drawn for the red light in (a)(iii). Mark both parts of this path with the letter V. [2] [Total: 9]

9 marks

Mark scheme: 7 (a) (i) light of a single wavelength / frequency ignore ‘one colour’ B1 (ii) n = sin i/sin r OR 1.52 = sin 50/sin r OR sin r = sin 50/1.52 C1 30.26º at least 2 s.f. A1 (iii) ray closer to normal in block B1 ray parallel to incident ray emerging from block B1 (b) (i) n = vA/vG OR n = 1.54/vG OR vG = 3 × 108/1.54 C1 1.948 × 108 m/s B1 (ii) ray with smaller angle of refraction than red in block i.e. violet ray under red ray B1 emerging ray parallel to incident ray B1 [9] IGCSE – October/November 2011 0625 31

This question in 0625/31 Oct/Nov 2011

6 Fig. 6.1 shows an enlarged view of a spherical raindrop, centre O. A air raindrop O Fig. 6.1 (a) On Fig. 6.1, draw a ray in the air striking the raindrop at A with an angle of incidence of 59° and coming from the left. [1] (b) The water in the raindrop has a refractive index of 1.33. (i) Show by calculation that the angle of refraction at A is about 40°. [2] (ii) On Fig. 6.1, draw the path of the refracted ray to the point where it strikes the inner surface of the raindrop. Label this point B. [1] (c) The ray is partially reflected at B. Draw the normal and the reflected ray at B. [1] (d) Extend the reflected ray to strike the surface of the raindrop again. At this point it is partially refracted out of the raindrop. Draw the approximate path of this ray as it emerges into the air. [1] [Total: 6]

6 marks

Mark scheme: 6 (a) incident ray correct at 59° B1 [1] (b) (i) use of n = sin i/sin r C1 (r = sin–1 (sin59/1.33)) = 40.1° condone no unit only accept 40° if working shown e.g. sin 59/1.33 A1 [2] (ii) ray from A to B AND angle of refraction = 40° B1 [1] (c) reflected ray at B, correct by eye B1 [1] (d) emerging ray refracted away from normal B1 [1]

This question in 0625/32 Oct/Nov 2011

9 Fig. 9.1 represents a ray of monochromatic light passing through a rectangular glass block. 45° glass block 26° α Fig. 9.1 (not to scale) (a) What is meant by the term monochromatic? … … [1] (b) Use the information on Fig. 9.1 to determine the refractive index of the glass. refractive index = … [2] (c) The angle α on Fig. 9.1 is not drawn with the correct value. State the correct value of angle α. α = … [1] (d) After the ray has left the glass block, it passes into a block of ice, whose refractive index is 1.31. How does the speed of light in ice compare with (i) the speed of light in air, … (ii) the speed of light in glass. … [2] [Total: 6]

6 marks

Mark scheme: 9 (a) single frequency / wavelength IGNORE single colour / chromatic B1 (b) sin i/sin r OR sin45/sin26 IGNORE sin r/sin i C1 1.613 A1 (c) 45° B1 (d) less / slower / smaller B1 more / faster / greater B1 [6]

This question in 0625/33 Oct/Nov 2011

7 Fig. 7.1 shows the principal axis PQ of a converging lens and the centre line XY of the lens. For Examiner’s Use X P Q Y Fig. 7.1 An object 2.0 cm high is placed 2.0 cm to the left of the lens. The converging lens has a focal length of 3.0 cm. (a) On Fig. 7.1, draw a full-scale diagram to find the distance of the image from the lens, For and the height of the image. Examiner’s Use distance of image from the lens = … height of image = … [5] (b) State and explain whether the image in (a) is real or virtual. … … [1] [Total: 6]

6 marks

Mark scheme: 7 (a) two of: ray through centre of lens undeviated ray parallel to axis refracted to right hand focus B2 rays through left hand focus refracted parallel to axis rays extrapolated to a point B1 accuracy marks: image 6 cm from lens B1 image 6 cm high B1 (b) image is virtual/not real AND cannot be seen on screen OR no rays come from (position of) image B1 [Total 6] IGCSE – May/June 2013 0625 31

This question in 0625/31 May/June 2013

6 (a) Fig. 6.1 shows two rays from a point object P incident on a water surface. For Examiner’s An observer sees the image of P produced by reflection at the surface of the water. Use P water air surface water Fig. 6.1 On Fig. 6.1, draw the reflected rays and complete the diagram to locate the position of the image. Label the position of the image I. [2] (b) Fig. 6.2 shows two rays from a point object Q incident on another water surface. An observer sees the image of Q produced by refraction at the surface of the water. water air surface water Q Fig. 6.2 On Fig. 6.2, draw possible refracted rays and complete the diagram to locate a possible position of the image. Label the position of the image J. You do not need to calculate any angles. [2] (c) The refractive index of water is 1.33. For Examiner’s Calculate the critical angle. Use critical angle = … [2] (d) Describe, with a diagram, a medical use of optical fibres. … … … … … [3] [Total: 9]

9 marks

Mark scheme: 6 (a) correct reflection of left ray AND 22° ≤ angle between right ray and surface ≤ 32°, by protractor B1 rays projected back to form image in correct position B1 [2] (b) both rays refract down M1 rays projected back to form image somewhere in water to the left of where left ray strikes surface A1 [2] (c) sin c = 1 / 1.33 OR sin c /sin r = 1 / 1.33 C1 OR sin–1 (1 / 1.33) OR sin–1 0.75 (c = 48.8° =) 49° A1 [2] (d) appropriate use, accept diagram accept ‘endoscope’, ‘in medicine’ is not sufficient M1 clear diagram of the above use or t.i.r. diagram for optical fibre A1 one from: light goes down fibre/into body illuminates internal organ light/image returns from body/organ o.w.t.t.e. A1 [3] [Total: 9] IGCSE – May/June 2013 0625 32

This question in 0625/32 May/June 2013

7 The frequency of the monochromatic light produced by a laser is 4.7 × 1014 Hz. For Examiner’s A ray of light from the laser passes from a vacuum, where the speed of light is 3.0 × 108 m / s, Use into a fibre-optic cable. (a) State (i) what is meant by monochromatic, … … [1] (ii) the frequency of light from the laser in the fibre-optic cable. … [1] (b) The speed of light in the fibre-optic cable is 2.0 × 108 m / s. Calculate (i) the refractive index of the material from which fibre-optic cable is made, refractive index = … [2] (ii) the wavelength of light from the laser in the fibre-optic cable. wavelength = … [2] [Total: 6]

6 marks

Mark scheme: 7 (a) (i) (only) one frequency (accept wavelength) B1 (ii) 4.7 × 1014 Hz OR the same as before OR unchanged B1 (b) (i) (n = )c/v OR 3.0 × 108 / 2.0 × 108 M1 1.5 A1 (ii) (λ = )c/f OR 2.0 × 108/4.7 × 1014 C1 4.3/4.26/4.255319 × 10–7 m A1 [6]

This question in 0625/33 May/June 2013

4 Fig. 4.1 shows a small, closed, transparent chamber containing smoke. For Examiner’s microscope Use smoke in chamber closed transparent bright light chamber Fig. 4.1 The chamber is brightly lit and observed through a microscope. The smoke particles are seen as very small, bright dots. (a) Describe the movement of the dots. … … … … [2] (b) Explain, in terms of molecules, how this movement is caused. … … … … [2] (c) Describe what is seen as the smoke particles move towards and away from the observer. … … … … [1] [Total: 5]

5 marks

Mark scheme: 4 (a) irregular / random / haphazard movement B1 any mention of different directions or clearly described B1 [2] (b) smoke particles condone atoms, molecules etc. AND (invisible) air molecules B1 air and smoke / dots collide ignore other collisions B1 [2] (c) dots move in or out of focus/disappear OR appear brighter / dimmer B1 [1] [Total: 5]

This question in 0625/32 Oct/Nov 2013

7 (a) Fig. 7.1 shows a ray diagram of a converging lens forming the image I of the object O. For Examiner’s Use C D B A O I observer’s eye Fig. 7.1 (i) Put a tick in two boxes in the following list to describe the image formed by the lens in Fig. 7.1. description place two ticks in this column real virtual magnified (enlarged) same size diminished (smaller) (ii) Which length, on Fig. 7.1, is the focal length of the lens? Circle one of the lengths below. AB BC BD CD [3] (b) In this question, you will apply the laws of reflection for a plane mirror to a curved mirror. For Examiner’s This mirror is shown in Fig. 7.2. The normal at any point on this mirror is the line from Use that point to the point C. mirror P O M C Fig. 7.2 Two rays have been drawn from the object O. On Fig. 7.2, (i) draw the normal to the mirror at M, [1] (ii) draw the ray reflected from M, [1] (iii) draw the ray reflected from P, [1] (iv) extend the reflected rays back to the right of the mirror and locate the image. Label this image I. [2] [Total: 8]

8 marks

Mark scheme: 7 (a) (i) BOX 2 ticked virtual B1 BOX 3 ticked magnified B1 (ii) AB circled B1 [3] (b) (i) normal at M towards C B1 [1] (ii) 40° ≤ angle of reflection ≤ 50° B1 [1] (iii) any clear indication that OP is also the reflected ray B1 [1] (iv) lines extended back from M and P to meet to the right of mirror AND indication of intersection as image position M1 image within 25 mm of right hand margin line AND higher than P but within 16 mm A1 [2] [Total: 8] IGCSE – October/November 2013 0625 32

This question in 0625/32 Oct/Nov 2013

7 A ray of light from a laser passes from air into a clear, semi-circular, plastic block. Fig. 7.1 For shows the ray entering the block. Examiner’s Use plastic block normal 40° light ray Fig. 7.1 The ray continues in the same direction and meets the middle of the opposite surface at an angle of 40 ° to the normal. The refractive index of the plastic is 1.5. (a) The ray continues into the air. Calculate the angle between the normal and the path taken by the light after it leaves the block. angle = … [3] (b) The frequency of the light produced by this laser is 3.8 × 1014 Hz and its wavelength in For the plastic block is 5.3 × 10–7 m (0.000 53 mm). Examiner’s Use Calculate (i) the speed of light in this plastic, speed = … [2] (ii) the speed of light in air. speed = … [2] (c) Explain why the ray does not change direction as it enters the plastic block. … … … [2] [Total: 9]

9 marks

Mark scheme: 7 (a) n = sin i/sin r or n = sin r/sin i or (sin i =) 1.5 sin 40(°) i or (sin r =) 1.5 sin 40(°) or 25° C1 0.9641 C1 75/74.6 ° to 2 or more sig. figs. A1 [3] (b) (i) (v =) fλ or 3.8 × 1014 × 5.3 × 10-7 C1 2.01 × 108 m / s to 2 or more sig. figs. A1 [2] (ii) (c =) nv or 1.5 × 2.0/2.01/2.014 × 108 (e.c.f. from 7(b)(i)) C1 3.02 × 108 m / s (accept 3 or 3.0 × 108 m / s only with working) (e.c.f. from 7(b)(i)) A1 [2] (c) wave(front) hits/enters the plastic at the same time or incident ray perpendicular along normal/at 90° or i = 0° (condone it doesn’t hit at an angle) B1 wave(front) all slows down at the same time or refracted ray perpendicular normal/at 90° or r = 0° by calculation B1 [2] [Total: 9]

This question in 0625/33 Oct/Nov 2013

6 (a) Fig. 6.1 shows a ray of light incident on the surface of a glass block. Fig. 6.1 On Fig. 6.1, accurately draw the reflected ray. [2] (b) Fig. 6.2 shows a ray of light incident on a glass prism. w v x u z y Fig. 6.2 Put one tick only in each line of the table to indicate which of the angles labelled in Fig. 6.2 are the angle of incidence and the angle of refraction. u v w x y z angle of incidence angle of refraction [2] (c) The refractive index of water is 1.33. A ray of light passes from water into air. The angle of incidence at the water-air interface is 30 °. Calculate the angle of refraction. angle of refraction = … [3] (d) Fig. 6.3 shows rays of violet and red light incident on a prism. The dashed line shows the path taken by the ray of violet light in the prism. path of rays of violet and red light Fig. 6.3 On Fig. 6.3, draw and label the path that the ray of red light takes in the prism. A calculation is not required. [2] [Total: 9]

9 marks

Mark scheme: 6 (a) reflected ray in correct quadrant B1 34° Y angle from surface Y 42° B1 ignore refracted ray for both marks (b) angle of incidence: any mark in v box only B1 angle of refraction: any mark in y box only B1 (c) sin i / sin r = n or sin i / sin r = 1 / n in any form C1 sin r = 1.33 sin 30 or (sin 30) / 1.33 or 0.665 or 0.376 C1 (r = )42° A1 (d) refracted down compared to incident ray ignore emerging ray M1 between dashed line and 25° above it ignore emerging ray A1 [Total: 9] rd

This question in 0625/32 May/June 2014

8 A lamp in a large room is suspended below a horizontal mirror that is fixed to the ceiling. Fig. 8.1 is a scale diagram of the lamp and mirror. reflecting surface of mirror lamp Fig. 8.1 An image of the lamp is formed by the mirror. (a) (i) On Fig. 8.1, draw two rays from the centre of the lamp that strike the mirror. Use these rays to locate the image. Label the image I. [3] (ii) State two characteristics of this image. 1. … 2. … [2] (b) Suggest an advantage of positioning a mirror above the lamp. … … [1] [Total: 6]

6 marks

Mark scheme: 8 (a) (i) two rays from lamp to mirror AND one good (i ≈ r) reflected ray B1 two good reflected rays AND rays traced back above mirror B1 labelled / clear image located at intersection AND in correct position B1 (ii) any two from: virtual (longitudinally) inverted same size (as lamp) OR same distance (from mirror) B2 (b) light reflected back / down OR not wasted OR room brighter OR more light etc. B1 [Total: 6] IGCSE – May/June 2014 0625 33

This question in 0625/33 May/June 2014

6 (a) Fig. 6.1 shows an object O placed in front of a plane mirror M. Two rays from the object to the mirror are shown. M O Fig. 6.1 (i) On Fig. 6.1, for one of the rays shown, 1. draw the normal to the mirror, 2. mark the angle of incidence. Label this angle X. [2] (ii) On Fig. 6.1, draw 1. the reflected rays for both incident rays, 2. construction lines to locate the image of O. Label this image I. [2] (b) In Fig. 6.2, circular wavefronts from a point source in a tank of water strike a straight barrier. barrier source Fig. 6.2 (i) The reflected wavefronts seem to come from a single point. On Fig. 6.2, mark a dot to show the position of this point. Label this point C. [1] (ii) Draw, as accurately as you can, the reflected circular wavefronts. [2] [Total: 7]

7 marks

Mark scheme: 6 (a) (i) 1. one normal to mirror drawn B1 2. angle of incidence, labelled X B1 (ii) 1. both reflected rays drawn B1 2. construction lines to locate image, marked I B1 (b) (i) dot marked C in correct position B1 (ii) two circular arcs each joining correct points on barrier B1 spacing of arcs same as spacing of incident waves B1 [Total: 7]

This question in 0625/31 Oct/Nov 2014

11 Fig. 11.1 shows part of the path of a ray of light PQ travelling in an optical fibre. Q glass P Fig. 11.1 (a) On Fig. 11.1, carefully complete the path of the ray of light, until it leaves this section of the optical fibre. [2] (b) The material of an optical fibre has a refractive index of 1.52. Calculate the critical angle. critical angle = … [2] (c) (i) State what sort of reflection takes place within an optical fibre. … [1] (ii) Explain your answer. … … [1] [Total: 6]

6 marks

Mark scheme: 11 (a) internal reflection AND i = r for 1st reflection NOT any ray emerges from sides M1 ray reaches end of tube after 1 or 2 reflections only A1 (b) sin–11/n OR Snell’s Law in any form C1 (c= sin–11 / 1.52 =) 41° B1 (c) (i) total internal reflection B1 (ii) angle of incidence > c OR light must reach end of fibre with small losses o.w.t.t.e. B1 [Total: 6]

This question in 0625/32 Oct/Nov 2014

5 Light enters a glass fibre from air at an angle of incidence of 62 °. The angle of refraction in the glass is 36 °. (a) The speed of light in air is 3.0 × 108 m / s. Determine the speed of light in the glass fibre. speed = … [4] (b) Describe how glass fibres are used in communications technology. … … … … [3] [Total: 7]

7 marks

Mark scheme: 5 (a) (n =) sin i / sin r OR sin 62 / sin 36 C1 1.5(02) C1 (vg =) c / n OR 3.0 × 108 / 1.5 C1 2.0 / 2.00 / 1.997 × 108 m / s A1 (b) (infra-red / light) encoded OR (sent as) pulses OR multiplexing OR many messages OR signal OR information OR data OR internet B1 (optical fibre transmits) light / infra-red (pulse) B1 total internal reflection / TIR (prevents escape) B1 [Total: 7]

This question in 0625/33 Oct/Nov 2014

6 Fig. 6.1 shows a glass block ABCD surrounded by air. A ray of red light, PQ, is incident on face CD of the block. A B D C Q P Fig. 6.1 (a) On Fig. 6.1, (i) draw the normal at Q and the refracted ray inside the block so that it meets face AB, (ii) draw the ray emerging from face AB of the block and the normal where the ray emerges, (iii) between the rays and the normals you have drawn, label two equal angles X. [3] (b) The angle of incidence of another red ray is 65°. The refractive index of the glass of block ABCD for red light is 1.62. (i) Calculate the angle of refraction in the glass for this ray. angle = … [2] (ii) The speed of light in air is 3.0 × 108 m / s. Calculate the speed of the red light in the glass. speed = … [2] (c) For the same angle of incidence, the angle of refraction of red light in glass is greater than the angle of refraction of violet light. State the term which describes the separation of red and violet refracted rays in glass. … [1] [Total: 8]

8 marks

Mark scheme: 6 (a) (i) Normal at Q drawn AND refracted ray drawn with r less than i B1 (ii) Emerging ray drawn parallel to PQ AND normal drawn B1 (iii) Two equal angles, marked X, between rays and normal B1 (b) (i) n = sin i ÷ sin r in any form OR 1.62 = sin 65 ÷ sin r in any form C1 OR sin r = sin 65 ÷ 1.62 r = 34° A1 (ii) n = speed (of light) in air ÷ speed (of light) in glass in any form C1 OR 1.62 = 3.0 × 108 ÷ speed in glass in any form (speed in glass = 3.0 × 108 ÷ 1.62) = 1.8 OR 1.9 × 108 m / s A1 (c) Dispersion B1 [Total: 8]

This question in 0625/32 Feb/March 2015

7 (a) Fig. 7.1 represents an object O placed in front of a converging lens. I O P Q R S Fig. 7.1 (i) State a full description of the image I. … [2] (ii) Using the letters on Fig. 7.1, identify the focal length of the lens. … [1] (iii) On Fig. 7.1, draw an eye suitably placed to view the image I. [1] (b) Fig. 7.2 shows an object O placed to the left of a converging lens. A principal focus of the lens is at the position marked F. O F Fig. 7.2 (i) On Fig. 7.2, draw two rays to locate the image of object O. Draw the image. (ii) On Fig. 7.2, draw one other ray from the upper tip of O to the image. [4] [Total: 8]

8 marks

Mark scheme: 7 (a) (i) all three of: max. B2 • virtual, • upright / erect / same way up, • magnified / large(r) (than object) award 1 mark for one or two correct description(s) which are not contradicted (ii) RS B1 (iii) eye placed to right of lens B1 (b) any two correct rays from: max. B2 • ray parallel to axis refracted through F • ray passing through centre of lens undeflected • ray through added focus to left of lens refracted parallel to axis image from intersection of rays clearly shown as inverted B1 3 correct rays drawn on Fig. 7.2, from tip of O to intersection of other two rays and refracted correctly at lens note: the third ray does not have to be one of those listed above B1 [Total: 8]

This question in 0625/31 May/June 2015

6 The refractive index n of glass in air is 1.5. (a) (i) State the equation that relates the speed of light in air va, the speed of light in glass vg and n. … [1] (ii) The speed of light in air is 3.0 × 108 m / s. Calculate the speed of light in glass. speed = … [1] (b) Light travelling in glass strikes the edge of the glass. Fig. 6.1 shows a ray of light at an angle of 41° to the normal. normal air glass 41° Fig. 6.1 (i) The light passes from the glass into the air. Calculate the angle that the ray makes with the normal in the air. angle = … [2] (ii) State what happens to light that strikes the edge of the glass at an angle to the normal much larger than 41°. … [1] (c) Describe one example of how optical fibres are used in medicine. … … … … [2] [Total: 7]

7 marks

Mark scheme: 6 (a) (i) n = va ÷ vg in any form B1 (ii) 2.0 × 108 OR 2 × 108 m / s B1 (b) (i) n = sin(i) ÷ sin(r) OR sin(r) = 1.5 × sin 41° OR sin–1(r) = 0.98 C1 (r =) 80° A1 (ii) total (internal) reflection OR no refraction OR all light reflected B1 (c) some indication of multiple reflections in optical fibre, accept from diagram B1 appropriate further information, e.g. endoscope OR looking/illuminating inside body B1

This question in 0625/32 May/June 2015

6 A glass, converging lens is used as a magnifying glass to observe a red ant. (a) Fig. 6.1 shows the lens, the principal axis, and the two principal focuses F1 and F2. F1 F2 principal axis lens Fig. 6.1 (i) 1. On Fig. 6.1, mark a point on the principal axis, labelled A, to indicate a suitable position for the ant. 2. On Fig. 6.1, mark a point on the principal axis, labelled E, to indicate a suitable position for the observer’s eye. [1] (ii) Tick one of the boxes to indicate where, on the principal axis, the image of the ant is located. to the left of F1 between F1 and the lens within the lens between the lens and F2 to the right of F2 [1] (iii) Underline two words in the list that describe the image produced by the magnifying glass. diminished inverted real upright virtual [2] (b) (i) The red light from the ant passes into the lens. As the light enters the lens, state what happens to 1. its wavelength, … [1] 2. its frequency. … [1] (ii) State how the wavelength of violet light in air differs from the wavelength of red light in air. … [1] [Total: 7]

7 marks

Mark scheme: 6 (a) (i) A (on principal axis) between the lens and one focal point B1 AND E somewhere on other side of lens (ii) on same side as A and further than the principal focus from lens B1 (iii) virtual underlined B1 upright underlined B1 (b) (i) 1. decreases/becomes smaller B1 2. stays the same/unchanged B1 (ii) smaller B1 [Total: 7]

This question in 0625/33 May/June 2015

7 (a) Fig. 7.1 shows a convex lens being used to produce an image of an object. principal focus image object Fig. 7.1 (i) Place three ticks in the table that describe this image. can only be formed on a screen diminished enlarged inverted real same size upright virtual [3] (ii) On Fig. 7.1, mark a letter E to indicate a possible position for an eye to be placed to observe this image. [1] (iii) State an application in which a convex lens is used in this way. … [1] (b) In the space below, draw a ray diagram to locate the image of an object of height 1.0 cm placed 5.0 cm from a convex lens of focal length 2.0 cm. Draw your diagram full size. You are advised to locate the lens roughly in the centre of the space. Label the image. [3] [Total: 8]

8 marks

Mark scheme: 7 (a) (i) boxes ticked: enlarged upright virtual B3 (ii) E marked anywhere to right of lens B1 (iii) magnifying glass(es) or lens / eyepiece of telescope / microscope / binoculars B1 (b) object in correct position and correct size and F in correct position from label or correct ray intersection with axis B1 two correct rays M1 image between 28 mm and 38 mm from lens and labelled as word or letter A1 [Total: 8] 5 7

This question in 0625/31 Oct/Nov 2015

8 (a) Fig. 8.1 is a ray diagram of a convex lens being used as a magnifying glass to produce a virtual image. Fig. 8.1 On Fig. 8.1, (i) label the object O, (ii) label the image I, (iii) label a principal focus F, (iv) put arrows on the two rays to indicate their directions. [4] (b) Fig. 8.2 shows a ray of light in air incident on an interface with glass. The refractive index of glass is 1.5. glass air incident ray Fig. 8.2 On Fig. 8.2, accurately draw the ray as it travels in the glass. You will need to take a measurement from Fig. 8.2 and carry out an appropriate calculation. Show your working. [3] [Total: 7]

7 marks

Mark scheme: 8 (a) (i) correct O label B1 (ii) correct I label B1 (iii) correct F label, allow correctly labelled dot to left of lens B1 (iv) correct arrows on both rays, anywhere on each ray B1 (b) 1 / n = sin i / sin r OR n = sin i / sin r in any form OR sin i / n OR n sin i C1 (r = sin-1 ((sin 35) / 1.5) =) 22° accept if in diagram A1 emergent ray drawn with 27° ≥ r ≥ 18° B1 [Total: 7]

This question in 0625/32 Oct/Nov 2015

7 (a) The refractive index of a type of glass is 1.6. Calculate the critical angle for light in this type of glass. critical angle = … [3] (b) A waterproof laser is immersed in water. Fig. 7.1 shows the laser shining light up towards the horizontal surface of the water. air water normal e beam of light movement of laser laser Fig. 7.1 Initially, the angle θ is much less than the critical angle for this light in water. The laser moves and θ gradually increases until it is much greater than the critical angle. Describe, for different angles of the laser, what happens to the light beam after it hits the surface. … … … … … … … [4] [Total: 7]

7 marks

Mark scheme: 7 (a) (α =) sin–1(1 / n) OR sin α = 1 / n OR sin90(°) / sin α = n C1 (C =) sin–1(1 / 1.6) C1 39° OR 38.7(38.682)° A1 (b) any four from: (initially / θ C) refracted ray / ray in air / ray emerges (initially / θ ≤ C) refracted ray / ray in air / ray emerges AND reflected ray (initially / θ C) angle of refraction increasing (initially / θ C) refracted ray gets weaker OR reflected rays gets stronger (θ = C) refracted ray along surface (eventually / θ > C / r > 90°) refracted ray disappears OR no more refraction OR does not emerge OR total internal reflection (description of) angle of reflection increasing OR always equals angle of incidence B4 [Total: 7]

This question in 0625/33 Oct/Nov 2015

6 (a) Fig. 6.1 shows a plane mirror reflecting a ray of light. x y mirror w z Fig. 6.1 (i) There is a dashed line drawn at right angles to the mirror. State the name of this line. … [1] (ii) State which angle, w, x, y, or z, is the angle of reflection. … [1] (b) Fig. 6.2 shows a ray of white light entering a semi-circular glass block. The ray of light emerges at point R and travels alongside the flat surface. screen S R T glass white light Fig. 6.2 A spectrum of colours can be seen on the screen between S and T. (i) State the colours in the correct order. One has been done for you. red colour at S … … … … … … colour at T … [1] (ii) The angle of the ray is changed. On Fig. 6.3, complete the path of the ray of light. Explain your answer. air glass white light Fig. 6.3 … … … [3] [Total: 6]

6 marks

Mark scheme: 6 (a) (i) (the) normal B1 (ii) y B1 (b) (i) (red), orange, yellow, green, blue, indigo, violet / purple B1 (ii) any three from: B3 (ON DIAGRAM) ray reflected angle i = angle r (by eye) explanation: (incident angle) is greater than critical angle (so there is) total internal reflection [Total: 6]

This question in 0625/32 Feb/March 2016

8 A student directs a ray of light towards a plane mirror, as shown in Fig. 8.1. plane mirror D E ray of light ; Fig. 8.1 (a) (i) Name the line labelled X. … [1] (ii) When angle a is 45°, angle b is also 45°. Angle a is changed to 20°. What is the new value of angle b? Tick one box. 20° 25° 45° 65° 80° [1] (b) The student now makes the ray of light from Fig. 8.1 pass into a glass block, as shown in Fig. 8.2. plane mirror glass block D E ray of 4 light 3 F G H 5 I J 7 6 Fig. 8.2 Complete the table, using the labels from Fig. 8.2. The first label is done for you. description label an angle of incidence a an angle of refraction an internally reflected angle a critical angle a refracted ray [4] (c) The student uses a converging lens to produce an image of an object. Fig. 8.3 shows the arrangement. key: F = principal focus O = object O F F Fig. 8.3 On Fig. 8.3, using a ruler, carefully draw two rays from the object O to locate the position of the image. Use an arrow to represent the image. [3] [Total: 9]

9 marks

Mark scheme: 8(a)(i) normal B1 8(a)(ii) 20° B1 8(b) d B1 g B1 f B1 R OR S B1 8(c) any two rays correctly drawn from top of O: ray parallel to axis, through lens, and beyond F ray undeviated through centre of lens and beyond ray through F, through lens, then parallel to axis M2 inverted image correctly drawn and positioned at intersection of two rays A1 Total: 9

This question in 0625/31 May/June 2016

7 Fig. 7.1 shows a ray of light incident on a rectangular glass block at point X. W P X air Q glass R S Fig. 7.1 The ray of light is refracted at X. On Fig. 7.1, (a) draw the normal at X, [1] (b) draw the path of the ray through the glass block until it reaches the surface RS, [1] (c) label, at X, the angle of incidence with a letter i and the angle of refraction with a letter r, [2] (d) draw the path of the ray of light leaving the glass block. [1] [Total: 5]

5 marks

Mark scheme: 7(a) normal drawn at X above and in the block B1 7(b) ray refracted toward normal drawn from X to side RS B1 7(c) angle of incidence correctly labelled angle of refraction correctly labelled B1 B1 7(d) ray drawn refracted away from the normal B1 Total: 5

This question in 0625/32 May/June 2016

7 Fig. 7.1 shows a ray of light incident on a rectangular glass block at point X. W P X air Q glass R S Fig. 7.1 The ray of light is refracted at X. On Fig. 7.1, (a) draw the normal at X, [1] (b) draw the path of the ray through the glass block until it reaches the surface RS, [1] (c) label, at X, the angle of incidence with a letter i and the angle of refraction with a letter r, [2] (d) draw the path of the ray of light leaving the glass block. [1] [Total: 5]

5 marks

Mark scheme: 7(a) normal drawn at X above and in the block B1 7(b) ray refracted toward normal drawn from X to side RS B1 7(c) angle of incidence correctly labelled angle of refraction correctly labelled B1 B1 7(d) ray drawn refracted away from the normal B1 Total: 5

This question in 0625/33 May/June 2016

6 A candle is placed in front of a vertical mirror. Fig. 6.1 shows a ray of light reflected from the mirror. mirror normal candle Fig. 6.1 (a) (i) On Fig. 6.1, draw an arrow on the ray to show the direction of travel of the ray of light. [1] (ii) On Fig. 6.1, label the angle of incidence i and the angle of reflection r. [1] (iii) Tick (✓) two boxes to describe the image of the candle in the mirror. closer to the mirror than the candle the same distance from the mirror as the candle on the surface of the mirror smaller than the candle the same size as the candle [2] (b) Other rays of light also strike the mirror and are reflected. State the rule that always links the angle of incidence and the angle of reflection. … [1] [Total: 5]

5 marks

Mark scheme: 6(a)(i) arrow on incident ray pointing towards mirror OR arrow on reflected ray pointing away from mirror B1 6(a)(ii) i AND r both correctly labelled B1 6(a)(iii) same distance from mirror as candle B1 same size as the candle B1 6(b) angle of incidence = angle of reflection B1 Total: 5

This question in 0625/33 Oct/Nov 2016

10 Fig. 10.1 shows two mirrors placed at right angles to each other. A ray of light is incident on mirror A, which is then reflected towards mirror B. mirror A 20° mirror B Fig. 10.1 (a) Determine the angle of incidence of the ray on mirror A. angle of incidence = … [1] (b) (i) The ray is also reflected from mirror B. On Fig. 10.1, continue the path of the ray of light. Show the position of the reflected ray and the normal to mirror B. [2] (ii) On Fig. 10.1, use the letter r to label the angle of reflection from mirror B. [1] (c) State the law you used to complete the ray diagram. … [1] [Total: 5]

5 marks

Mark scheme: 10(a) B1 10(b)(i) normal correctly positioned on B B1 reflected ray drawn correctly B1 10(b)(ii) r labelled correctly B1 10(c) i = r / angle of incidence = angle of reflection B1 Total: 5

This question in 0625/32 Feb/March 2017

6 (a) Fig. 6.1 shows an overhead view of two cars approaching a road junction. A plane mirror helps the drivers to see other cars. plane mirror ray of light from car 1 road driver 2 car 2 driver 1 car 1 tall building Fig. 6.1 (i) A ray of light from car 1 is shown. On Fig. 6.1, clearly draw the normal to the plane mirror where this ray hits the plane mirror. Label the normal N. [1] (ii) On Fig. 6.1, carefully draw the reflected ray of light. [1] (iii) State the law used in your answer to (a)(ii). … [1] (iv) Can each driver see the other car? … Explain your answer. … [1] (b) Fig. 6.2 shows a ray of light incident on a glass block. glass block ray of light Fig. 6.2 (i) On Fig. 6.2, continue the path of the ray into the block. [1] (ii) On Fig. 6.2, clearly label the angle of incidence i and the angle of refraction r. [2] [Total: 7]

7 marks

Mark scheme: 6(a)(i) normal line drawn at 90° to mirror by eye B1 6(a)(ii) reflected ray drawn with i = r by eye B1 6(a)(iii) angle of incidence = angle of reflection B1 6(a)(iv) Mark is for the explanation linked to candidate’s diagram. e.g. if answer is YES they should state that the reflected ray hits/reaches the (other)driver/car or can be seen B1 6(b)(i) ray refracted toward the normal B1 6(b)(ii) angle of incidence labelled B1 angle of refraction labelled B1 Total: 7

This question in 0625/32 May/June 2017

6 (a) The diagrams in Fig. 6.1 show reflection, refraction and diffraction. On Fig. 6.1, write the correct word next to each diagram for the process shown. barrier … ray of light … ray of light air … water Fig. 6.1 [3] (b) Fig. 6.2 shows a transverse wave. displacement 0 distance Fig. 6.2 (i) On Fig. 6.2, label the amplitude of the wave. [1] (ii) On Fig. 6.2, label the wavelength of the wave. [1] (c) A thin converging lens forms an image of an object, as shown in Fig. 6.3. lens X object image Y Fig. 6.3 Only one ray is shown in Fig. 6.3. On Fig. 6.3, draw two more rays from point X on the object that can be used to locate point Y on the image. [2] [Total: 7]

7 marks

Mark scheme: 6(a) B1 middle diagram labelled reflection B1 bottom diagram labelled refraction B1 6(b)(i) amplitude correctly indicated by eye B1 6(b)(ii) wavelength correctly indicated by eye B1 6(c) straight line (by eye) drawn through centre of lens to Y B1 sloping ray that emerges horizontally from lens to Y B1 Total: 7

This question in 0625/33 May/June 2017

6 (a) Fig. 6.1 shows a ray of light inside a semi-circular glass block. air glass Fig. 6.1 The angle of incidence at the straight surface is less than the critical angle for the glass. On Fig. 6.1, continue the path of the ray. [2] (b) Fig. 6.2 shows another ray of light inside a semi-circular glass block. air glass Fig. 6.2 The angle of incidence at the straight surface is greater than the critical angle for the glass. (i) On Fig. 6.2, continue the path of the ray. [2] (ii) State the term used to describe what happens to the light when it strikes the straight surface in Fig. 6.2. … [1] (c) A wave on the surface of water approaches a barrier. There is a small gap in the barrier, as shown in Fig. 6.3. barrier water wave gap Fig. 6.3 On Fig. 6.3, draw three wavefronts that have passed through the gap. [2] [Total: 7]

7 marks

Mark scheme: 6(a) ray leaves glass at top surface B1 ray refracted away from normal B1 6(b)(i) ray reflected into glass B1 angle i = angle r by eye B1 6(b)(ii) total internal reflection B1 6(c) waves with arcs centred on gap B1 same wavelength B1

This question in 0625/31 Oct/Nov 2017

6 Fig. 6.1 shows a ray of light reflected from mirror 1 at point P and striking mirror 2 at point Q. 45° P plane mirror 1 ray of light plane mirror 2 Q Fig. 6.1 (a) On Fig. 6.1, • clearly mark the position of the normal at Q, • draw the ray reflected from point Q, • mark the angle of reflection at Q using the letter r, State the law you used to draw the reflected ray. … [4] (b) Compare the direction of the ray reflected from mirror 2 at Q with the direction of the ray incident on mirror 1 at P. Tick one box. The ray of light reflected from mirror 2 is parallel to the incident ray at P, perpendicular to the incident ray at P, at an angle of 45° to the incident ray at P. [1] (c) A thin, converging lens forms an image, I, of an object, O, as shown in Fig. 6.2. 24 cm 10 cm 8 cm O I Fig. 6.2 (i) On Fig. 6.2, label a principal focus of the lens, using the letter F. [1] (ii) State the focal length of the lens. focal length = … cm [1] [Total: 7]

7 marks

Mark scheme: 6(a) normal correctly positioned B1 6(a)(ii) correct reflected ray at 45° to normal B1 6(a)(iii) r correctly indicated B1 6(a)(iv) angle i = angle r B1 6(b) parallel to the incident ray at P B1 6(c) F correctly labelled / 10 cm from lens B1 10 (cm) B1

This question in 0625/32 Oct/Nov 2017

8 Fig 8.1 shows two parallel rays of light that pass through a thin converging lens. The diagram is incomplete. There is a principal focus at f1 and at f2. C X Y f1 f2 Fig. 8.1 (a) (i) On Fig. 8.1, complete the ray diagram to show how the lens focuses the light. [3] (ii) Which distance on Fig. 8.1 is a focal length of the lens? Tick (✓) one box. C to f2 f1 to f2 f2 to Y [1] (b) (i) A ray of light travels through a semicircular glass block, as shown in Fig. 8.2. z air glass block Fig. 8.2 State the term given to the angle of incidence labelled z. … [1] (ii) Fig. 8.3 shows another ray of light travelling in the semicircular glass block. air glass block Fig. 8.3 The angle of incidence is greater than z. Continue the path of the ray of light until it leaves the block. [2] [Total: 7]

7 marks

Mark scheme: 8(a)(i) top ray passes through f2 B1 bottom ray passes through f2 B1 refraction correctly shown either at centre of lens OR at both edges of lens B1 8(a)(ii) C to f2 B1 8(b)(i) critical angle B1 8(b)(ii) ray internally reflected B1 reflecting angle = incident angle B1

This question in 0625/33 Oct/Nov 2017

7 The spectrum of white light is made up of seven colours. (a) Fig. 7.1 shows a partially-completed spectrum. Two labels are missing. violet indigo green orange red Fig. 7.1 (i) On Fig. 7.1, write the name of the missing colour in each blank space. [2] (ii) On Fig. 7.1, indicate the direction of increasing wavelength for the spectrum. Draw an arrow in the box below the spectrum of colours. [1] (b) A ray of red light strikes one face of a triangular glass prism as shown in Fig. 7.2. ray of red light glass prism Fig. 7.2 (i) On Fig. 7.2, draw the path of the ray as it travels through the glass prism and enters the air. [2] (ii) State the term used to describe what happens to the ray of red light as it enters and leaves the prism. … [1] [Total: 6]

6 marks

Mark scheme: 7(a)(i) blue between indigo and green 1 yellow between green and orange 1 7(a)(ii) arrow pointing right 1 7(b)(i) ray(s) refracted down at first boundary (air/glass) 1 correct refraction for candidate’s ray (in glass prism) 1 7(b)(ii) refraction 1

This question in 0625/31 May/June 2018

5 Fig. 5.1 represents an object positioned on the principal axis of a thin lens. principal axis object F F Fig. 5.1 Each small square of the grid represents 0.5 cm. Each principal focus of the lens is labelled F. (a) Use the grid to determine the focal length of the lens. focal length = … cm [1] (b) (i) On Fig. 5.1, draw a ray from the top of the object that passes through a principal focus, then through the lens and beyond it. [1] (ii) On Fig. 5.1, draw a second ray from the top of the object that passes through the centre of the lens. Continue the path of this ray to the edge of the grid. [1] (iii) On Fig. 5.1, draw an arrow to show the position and nature of the image produced by the lens. [2] [Total: 5]

5 marks

Mark scheme: 5(a) (focal length =) 5 (cm) 1 5(b)(i) straight line through F and then parallel to PA from centre of lens 1 5(b)(ii) straight line from top of object through centre of lens 1 5(b)(iii) image indicated at point where rays cross 1 arrow drawn inverted on RHS of lens 1

This question in 0625/32 May/June 2018

6 (a) Fig. 6.1 shows a ray of red light incident on part of a lens. lens red light Fig. 6.1 (i) On Fig. 6.1, continue the path of the ray as it passes through the lens and emerges from it. [2] (ii) State the term used to describe the process as the ray enters and leaves the lens. … [1] (b) Fig. 6.2 shows two parallel rays of light travelling towards another lens. Fig. 6.2 The two rays of light pass through the lens to form an image. On Fig. 6.2, continue the path of the rays. Extend the rays for at least 5 cm beyond the lens. [2] [Total: 5]

5 marks

Mark scheme: 6(a)(i) refracted at first boundary correctly B1 refracted at second boundary correctly B1 6(a)(ii) refraction B1 6(b)(i) converging / bent inwards / meet at a point e.g. focus B1 6(b)(ii) two straight rays drawn converging B1

This question in 0625/32 Oct/Nov 2018

7 (a) A ray of white light is incident on a glass prism. It forms a spectrum that is visible on the screen. Fig. 7.1 shows the arrangement. screen narrow slit ray of white light red violet Fig. 7.1 Two of the colours in the visible spectrum are listed in the box below. Complete the box. List the five missing colours of the visible spectrum, in the correct order. red … … … … … violet [2] (b) Electromagnetic radiation has many uses. (i) Draw a line from each use to the type of radiation it requires. use type of radiation radio waves detecting an intruder at night microwaves infra-red communicating by satellite visible light for a telephone ultraviolet detecting broken bones in X-rays the body gamma rays [3] (ii) The types of radiation listed in (b)(i) form the electromagnetic spectrum. amplitude frequency velocity Complete the sentence. Choose a word from the box. The position of each type of radiation in the electromagnetic spectrum depends on its … . [1] [Total: 6]

6 marks

Mark scheme: 7(a) orange yellow green blue indigo B2 7(b)(i) detecting an intruder to infra-red B1 communicating by satellite to microwaves B1 detecting broken bones to X-rays B1 7(b)(ii) frequency B1

This question in 0625/32 Oct/Nov 2018

6 (a) Fig. 6.1 shows a ray of green light hitting a glass prism. screen normal ray of green light Fig. 6.1 (i) On Fig. 6.1, label the angle of incidence for the ray, using the letter, i. [1] (ii) On Fig. 6.1, complete the path of the ray of green light until it hits the screen. [2] (b) The ray of green light is replaced with a ray of white light. (i) The white light splits into a spectrum of colours. State the term used to describe this effect. … [1] (ii) State the colour that is refracted most by the prism. … [1] [Total: 5]

5 marks

Mark scheme: 6(a)(i) i placed between incident ray and normal B1 6(a)(ii) ray refracted towards normal at 1st surface B1 ray refracted down at 2nd surface B1 6(b)(i) dispersion B1 6(b)(ii) violet B1

This question in 0625/33 Oct/Nov 2018

6 Fig. 6.1 shows a ray of light that is reflected by a mirror. Y Z mirror ray of light line X Fig. 6.1 (a) (i) State the name of line X shown on Fig. 6.1. … [1] (ii) State the name of angle Y shown on Fig. 6.1. … [1] (iii) A student moves the ray of light and doubles the size of angle Y. State the effect on angle Z. … [1] (b) Fig. 6.2 shows a converging lens used to form an image I of an object O. object O F F image I lens Fig. 6.2 (i) State the name of the points labelled F on Fig. 6.2. … [1] (ii) Describe the nature of the image I. … … … [2] [Total: 6]

6 marks

Mark scheme: 6(a)(i) normal B1 6(a)(ii) (angle of) incidence B1 6(a)(iii) double(s) B1 6(b)(i) principal focus B1 6(b)(ii) inverted diminished B2

This question in 0625/32 May/June 2019

7 Fig. 7.1 shows a ray of red light being reflected at the flat surface of a glass block. glass block ray of air red light Fig. 7.1 (a) Explain why the ray of red light is totally internally reflected by the surface of the glass block. … … [1] (b) A ray of white light passes through a prism and produces a spectrum of colours on a screen, as shown in Fig. 7.2. screen ray of white light A spectrum of colours B Fig. 7.2 (i) State the name of the process of separating white light into a spectrum. … [1] (ii) Write the names of the seven colours that appear on the screen between A and B. colour at A … … … … … … colour at B … [1] (c) Visible light is one part of the electromagnetic spectrum. State the name of one other part of the electromagnetic spectrum and describe a use of this type of radiation. name of radiation … use of radiation … [2] [Total: 5]

5 marks

Mark scheme: 7(a) Any one from: angle of incidence is greater than the critical angle light is travelling from a(n optically) more dense medium to(wards an optically) less dense medium (at a large angle) B1 7(b)(i) dispersion B1 7(b)(ii) From A to B: red, orange, yellow, green, blue, indigo, violet B1 7(c) correct name for any part of em spectrum other than visible light M1 correct use of named part of em spectrum A1

This question in 0625/33 May/June 2019

8 (a) Fig. 8.1 shows an incomplete ray diagram of a converging lens forming an image of the object, O. O X Y lens Fig. 8.1 (i) State the term given to the line XY. … [1] (ii) On Fig. 8.1, indicate the position of one principal focus of the lens. Label the principal focus, F. [1] (b) (i) On Fig. 8.1, draw a ray of light from the top of the object that passes through the lens to form the image. Use a ruler. [2] (ii) On Fig. 8.1, draw the image formed by the lens. Label the image I. [1] (iii) Choose words from the box that describe the image formed by the lens in Fig. 8.1. diminished enlarged horizontal inverted same size upright Draw a ring around each correct word. [2] [Total: 7]

7 marks

Mark scheme: 8(a)(i) (principal) axis ignore X-axis B1 8(a)(ii) F marked near intersection of ray and principle axis B1 8(b)(i) Either: ray from top of object towards centre of lens B1 continues from centre and crosses initial ray B1 OR 1st ray through F on left of lens (needs to be added by candidate) (B1) 2nd ray parallel to principle axis and crosses initial ray (B1) 8(b)(ii) inverted arrow drawn from axis to point where rays cross B1 8(b)(iii) diminished circled B1 inverted circled B1

This question in 0625/33 May/June 2019

6 Fig. 6.1 shows a mirror periscope. The periscope is used to view a golfer over the heads of other people. The periscope has two plane mirrors each at an angle of 45° to the vertical. periscope 45° ray of light plane mirror golfer 45° plane mirror Fig. 6.1 (not to scale) (a) (i) On Fig. 6.1: 1. Continue the ray of light from the golfer towards the upper mirror of the periscope 2. Draw and label the normal at the point where the ray strikes the mirror. [1] (ii) On Fig. 6.1, continue the ray of light after reflection at the upper mirror until it leaves the periscope. [1] (iii) State the law of reflection used to deduce the position of the ray of light after striking the mirrors. … [1] (b) Fig. 6.2 shows three rays of red light each entering a semi-circular glass block. air X semi-circular glass block ray of red light air Y semi-circular glass block ray of red light air Z semi-circular glass block ray of red light Fig. 6.2 Table 6.1 angle of incidence description X less than the critical angle Y equal to the critical angle Z greater than the critical angle Using the information in Table 6.1, draw on Fig. 6.2 to complete the path of each ray of red light. [3] [Total: 6]

6 marks

Mark scheme: 6(a)(i) straight line to mirror AND normal correctly positioned B1 6(a)(ii) two correct reflections drawn B1 6(a)(iii) angle of incidence = angle of reflection B1 6(b) refracted away from normal B1 refracted along straight edge B1 totally internally reflected B1

This question in 0625/31 Oct/Nov 2019

7 An object, OX, is placed in front of a converging lens. Fig. 7.1 shows a ray of light from the object passing through the lens. X O Fig. 7.1 (a) (i) The lens forms an image of object OX. On Fig. 7.1, draw another ray from X to locate the position of the image. [1] (ii) On Fig. 7.1, draw an arrow to represent the image of OX and label it I. [1] (iii) On Fig. 7.1, mark a principal focus for the lens and label it F. [1] (iv) On Fig. 7.1, measure and record the focal length of the lens. focal length = … cm [1] (b) Describe the image I. Choose words from the list. Tick (✓) two boxes. enlarged diminished same size inverted upright [2] [Total: 6]

6 marks

Mark scheme: 7(a)(i) ray from X through centre of lens B1 7(a)(ii) image drawn from axis to point where rays cross and labelled I B1 7(a)(iii) point labelled F where ray crosses principal axis B1 7(a)(iv) 2.7 (cm) ± 0.2 cm B1 7(b) diminished 2nd box ticked B1 inverted 4th box ticked B1

This question in 0625/31 Oct/Nov 2019

8 Fig. 8.1 is a partially completed ray diagram. Object C F2 I O F1 Fig. 8.1 The object is at O and its image is at I. (a) Which distance is the focal length of the lens? Tick one box. C to F1 O to C F2 to I O to I [1] (b) On Fig. 8.1, extend the two rays from the arrowhead on the object until both reach the position of the image. [3] (c) The object is moved a small distance away from the lens. State the effect, if any, this has on the position and size of the image. position … size … [2] [Total: 6]

6 marks

Mark scheme: 8(a) top box ticked C to F1 B1 8(b) Diagonal ray through F1 to lens then parallel to optical axis to I. B1 ray parallel to principal axis to lens then refracted through F2 to I B1 both rays meet at arrowhead of image B1 8(c) (image) closer (to lens / F2) owtte (image) smaller B1 B1

This question in 0625/32 Oct/Nov 2019

8 Fig. 8.1 shows a ray of light travelling through a glass block and then reflecting from a mirror. mirror R T S P Q glass block M N Fig. 8.1 (a) State the term used for the dashed lines drawn in Fig. 8.1. … [1] (b) Use Fig. 8.1 to identify the three angles in the list. Place the correct letter in the box to indicate each angle. angle of incidence angle of reflection angle of refraction [3] (c) The ray of light in Fig. 8.1 changes direction as it enters the glass block. State the name of this effect and explain why it happens. name of effect … explanation … … … [2] [Total: 6]

6 marks

Mark scheme: 8(a) normal B1 8(b) angle of incidence: N angle of reflection: S angle of refraction: P B1 B1 B1 8(c) refraction change in speed OR different refractive indices B1

This question in 0625/33 Oct/Nov 2019

9 (a) Fig. 9.1 shows two rays of light X and Y leaving an object O. The rays strike a plane mirror. Ray X is reflected as shown. plane mirror ray of light X O ray of light Y Fig. 9.1 (i) On Fig. 9.1, draw the normal at the point where ray X strikes the mirror. [1] (ii) On Fig. 9.1, draw the path of ray Y after it strikes the mirror. [1] (b) An object O is placed on the left of a thin converging lens. F is the principal focus. This arrangement is shown in Fig. 9.2. lens O F Fig. 9.2 Two rays from the top of the object are incident on the lens, as shown in Fig. 9.2. On Fig. 9.2, draw the path of each ray to locate the position of the image of O formed by the lens. On Fig. 9.2, draw an arrow to represent the image and label it I. [3] [Total: 5]

5 marks

Mark scheme: 9(a)(i) normal at X correct by eye B1 9(a)(ii) reflected ray for Y has angle i = angle r by eye B1 9(b) horizontal ray drawn to continue through F B1 ray to centre drawn to continue undeviated B1 image drawn correctly where rays cross B1

This question in 0625/32 Feb/March 2020

7 (a) Fig. 7.1 shows a ray of light striking a plane mirror at point P. P 30° ray of light Fig. 7.1 (not to scale) (i) Determine the value of the angle of incidence for the ray of light at point P. angle of incidence = … ° [1] (ii) On Fig. 7.1, • draw a normal at point P • draw the ray reflected at point P • determine the angle of reflection at point P. angle of reflection = … ° [3] (b) Fig. 7.2 shows an object OB positioned 20 cm from a thin converging lens. Both principal focuses of the lens are labelled F. B O F F Fig. 7.2 Two rays from the tip B of the object are incident on the lens, as shown in Fig. 7.2. On Fig. 7.2, continue the paths of these two rays to show the position of the image of OB formed by the lens. Draw an arrow to show the size, position and orientation of the image of OB. [4] [Total: 8]

8 marks

Mark scheme: 7(a)(i) 60(°) B1 7(a)(ii) normal correctly positioned B1 correct reflected ray at 60° to normal B1 same value as (i) B1 7(b) horizontal ray drawn to continue through F B1 ray through principal focus continues parallel to axis B1 image indicated in correct position B1 image indicated with correct orientation B1

This question in 0625/31 May/June 2020

5 Fig. 5.1 shows a ray of red light passing through a semicircular glass block. air ray of red light q p r s semicircular glass block Fig. 5.1 (a) (i) State the term for the dotted line shown in Fig. 5.1. … [1] (ii) State which angle p, q, r or s is the angle of incidence for the ray of red light. … [1] (iii) State which angle p, q, r or s is the angle of refraction. … [1] (iv) State what happens to the speed of the red light as it enters the semicircular glass block from the air. … [1] (b) Fig. 5.2 shows the path of a ray of light entering a semicircular glass block. The critical angle for the glass block is 42°. On Fig. 5.2, continue the path of the ray. Show clearly its direction on leaving the glass block. ray of light 62° semicircular glass block Fig. 5.2 [2] (c) A ray of white light passes through two prisms as shown in Fig. 5.3. prisms D E F ray of white light Fig. 5.3 Draw one line to link the letter for each position to the correct effect at that position. position effect (i) refraction D diffraction total internal reflection [1] (ii) reflection E dispersion diffraction [1] (iii) red, green and blue light only produced F white light produced spectrum of visible light produced [1] [Total: 9]

9 marks

Mark scheme: 5(a)(i) normal B1 5(a)(ii) p B1 5(a)(iii) r B1 5(a)(iv) speed decreases B1 Question Answer Marks 5(b) reflects off flat surface at same angle (by eye) B1 passes through curved surface without deviation B1 5(c)(i) D – total internal reflection B1 5(c)(ii) E – dispersion B1 5(c)(iii) F – spectrum of visible light B1

This question in 0625/32 May/June 2020

7 (a) Fig. 7.1 shows a ray of light incident on a plane mirror at point X. plane mirror X 40° ray of light Fig. 7.1 (not to scale) (i) Determine the value of the angle of reflection for the ray of light at point X. … [1] (ii) On Fig. 7.1: • draw the normal at point X and label the normal with the letter N • draw the ray reflected from point X. [2] (b) Fig. 7.2 shows how a converging lens forms an image of an object. 28 cm 12 cm 9.0 cm object image Fig. 7.2 (not to scale) (i) Determine the focal length of the lens. focal length = … cm [1] (ii) Determine the distance of the image from the lens. distance = … cm [1] (iii) Describe the nature of the image formed by the lens in Fig. 7.2. … … … [2] [Total: 7]

7 marks

Mark scheme: 7(a)(i) 50° B1 7(a)(ii) normal correctly positioned B1 correct reflected ray at 50° to normal B1 7(b)(i) 12 (cm) B1 7(b)(ii) 21 (cm) B1 7(b)(iii) inverted B1 smaller / diminished B1

This question in 0625/31 Oct/Nov 2020

8 Fig. 8.1 shows a converging lens and an object. The side of each square represents 0.5 cm. lens object Fig. 8.1 (a) Using Fig. 8.1, determine the distance of the object from the centre of the lens. distance = … cm [2] (b) Fig. 8.2 shows another lens forming the image IY of object OP. P I O Y Fig. 8.2 (i) On Fig. 8.2, draw an arrow to represent the focal length of the lens. Label this arrow f. [2] (ii) Circle two words or phrases from those shown to describe the image formed in Fig. 8.2. enlarged upright inverted same size diminished [2] [Total: 6]

6 marks

Mark scheme: 8(a) 8.5 to 9.1 squares counted C1 4.5 (cm) A1 8(b)(i) focal length marked from centre of lens B1 to point where ray parallel to axis is refracted by lens to cross axis B1 8(b)(ii) inverted (third word circled) B1 diminished (5th / last word circled) B1

This question in 0625/32 Oct/Nov 2020

7 (a) Complete the following sentences about light. Use words from the list. atomic blue three electromagnetic electronic violet five red seven Light is part of a spectrum of radiation called the … spectrum. A glass prism disperses white light into … colours. The colour of light that is refracted least is … . [3] (b) Fig. 7.1 shows light reflected by a plane mirror. normal ray of light C B A D plane mirror Fig. 7.1 (i) State which angle A, B, C or D is the angle of incidence. … [1] (ii) State which angle A, B, C or D is the angle of reflection. … [1] [Total: 5]

5 marks

Mark scheme: 7(a) electromagnetic B1 seven B1 red B1 7(b)(i) B B1 7(b)(ii) C B1

This question in 0625/33 Oct/Nov 2020

6 Fig. 6.1 shows the path of a ray of red light through a glass block in air. The critical angle for the red light as it travels from glass into air is 43°. air B P 62° C A glass block ray of red light Fig. 6.1 (a) (i) On Fig. 6.1, label the angle of incidence at A. Use the letter X to label the angle. [1] (ii) State the name of the process which occurs at A. … [1] (iii) State the name given to the dashed line at A. … [1] (b) (i) On Fig. 6.1, one of the angles at B is 62°. State the value of the angle labelled P. … [1] (ii) State the name of the process which occurs at B. … [2] (c) On Fig. 6.1, draw the path of the ray of red light as it travels from C into the air. [1] [Total: 7]

7 marks

Mark scheme: 6(a)(i) angle of incidence correctly identified (with × between normal and incident ray) B1 6(a)(ii) refraction B1 6(a)(iii) normal (line) B1 6(b)(i) 62° B1 6(b)(ii) reflection C1 total internal reflection A1 6(c) ray refracted away from normal B1

This question in 0625/32 Feb/March 2021

7 A narrow beam of white light enters a glass prism and splits into the colours of the visible spectrum, as shown in Fig. 7.1. glass prism colours of visible spectrum beam narrow light white of Fig. 7.1 (a) The rays leaving the prism represent the seven main colours of the visible spectrum. Complete the labelling on Fig. 7.1 by writing the colours of the visible spectrum in the table. [2] (b) State the term used to describe: (i) the bending of the light as it enters the prism … [1] (ii) the different amounts of bending that produce the spectrum. … [1] (c) A student incorrectly writes some sentences about electromagnetic waves. His teacher circles a mistake in each sentence. In the table, write a suitable correction for each mistake. The first one has been done for you. student’s sentences correction the speed of light is faster than radio waves in a the same as vacuum X-rays are used in television remote controllers radio waves have the highest frequencies in the electromagnetic spectrum [2] [Total: 6]

6 marks

Mark scheme: 7(a) any 6 correct colours from: red, orange, yellow, green, blue, indigo, violet M1 candidate’s colours in correct order A1 7(b)(i) refraction B1 7(b)(ii) dispersion B1 7(c) infrared (rays/waves) (are used in tv remote controllers) B1 gamma (rays/waves) (have the highest frequencies in em spectrum) B1

This question in 0625/31 May/June 2021

8 A student uses a semicircular glass block to investigate refraction. (a) He shines a ray of red light into the block, as shown in Fig. 8.1. X is the middle of the flat surface. flat surface air X glass ray of red light Fig. 8.1 (i) On Fig. 8.1, draw the normal where the ray meets the flat surface at X. [1] (ii) On Fig. 8.1, label the angle of refraction. Use the letter R for the label. [1] (iii) The student uses a semicircular glass block. State the name of one other piece of equipment that he needs for the investigation. … [1] (b) Fig. 8.2 shows a ray of red light incident on the flat surface of the semicircular glass block. The angle of incidence is greater than the critical angle for glass. air X glass ray of red light Fig. 8.2 On Fig. 8.2, draw the path of the ray after it strikes the flat surface. [2] [Total: 5]

5 marks

Mark scheme: 8(a)(i) 8(a)(ii) angle of refraction correctly labelled B1 Question Answer Marks 8(a)(iii) any one from: • pin(s) OR ray box owtte OR (low voltage) power supply OR • protractor OR ruler B1 8(b) ray reflected from flat surface M1 ray reflected with angle i = angle r A1

This question in 0625/32 May/June 2021

8 (a) Fig. 8.1 shows a ray of light incident on a plane mirror. X a plane mirror b c ray of light Fig. 8.1 (i) State which angle, a, b or c, is the angle of incidence. angle of incidence = … [1] (ii) State the name of the line labelled X. … [1] (iii) The mirror reflects the ray of light. On Fig. 8.1, draw the reflected ray. [2] (b) Fig. 8.2 shows a ray of red light travelling through a semicircular glass block. air 42° glass ray of block red light Fig. 8.2 (i) Fig. 8.3 shows another ray of red light entering the semicircular glass block at 60°. Continue the path of this ray through the glass block and into the air. air 60° ray of red light glass block Fig. 8.3 [2] (ii) Fig. 8.4 shows another ray of red light entering the semicircular glass block at 20°. Continue the path of this ray through the glass block and into the air. air 20° glass ray of block red light Fig. 8.4 [2] [Total: 8]

8 marks

Mark scheme: 8(a)(i) c B1 8(a)(ii) normal B1 8(a)(iii) reflected ray a continuation of incident ray AND in correct quadrant M1 angle of reflection equals angle of incidence A1 Question Answer Marks 8(b)(i) continuation of incident ray AND reflected internally in correct quadrant M1 angle of reflection equals angle of incidence A1 8(b)(ii) continuation of incident ray AND emerging from block in correct quadrant M1 angle of refraction larger than angle of incidence A1

This question in 0625/33 May/June 2021

7 Fig. 7.1 shows a ray of red light entering a semicircular glass block. The ray strikes the flat surface of the block at X and emerges into the air. Fig. 7.1 does not show the path of the refracted ray in the air. normal air X glass ray of red light Fig. 7.1 (a) On Fig. 7.1: (i) draw the path of the refracted ray in the air [1] (ii) mark, and label with the letter i, the angle of incidence [1] (iii) mark, and label with the letter r, the angle of refraction. [1] (b) When the angle of incidence at X is 70°, the ray does not emerge from the glass into the air. State what happens to the ray at X and explain why this happens. … … … [2] (c) Visible light is one part of the electromagnetic spectrum. X‑rays are also part of the electromagnetic spectrum. (i) Visible light and X‑rays are travelling through a vacuum. Compare their speed and frequency by completing the sentences. The speed of visible light is … the speed of X‑rays. The frequency of visible light is … the frequency of X‑rays. [2] (ii) Describe one use of X‑rays. … [1] [Total: 8]

8 marks

Mark scheme: 7(a)(i) ray drawn refracted away from normal B1 7(a)(ii) angle of incidence correctly identified B1 7(a)(iii) angle of refraction correctly identified B1 7(b) total internal reflection (at flat surface) B1 angle (of incidence) is greater than the critical angle B1 7(c)(i) (The speed of visible light is) same (as) (the speed of X-rays.) B1 (The frequency of visible light is) lower OR smaller (than the frequency of X-rays) B1 7(c)(ii) example of medical / security imaging or treatment of cancer B1

This question in 0625/31 Oct/Nov 2021

9 (a) Fig. 9.1 shows a ray of light reflected by a plane mirror. normal plane mirror a d c b ray of light Fig. 9.1 (i) State which angle, a, b, c or d, is the angle of incidence. … [1] (ii) State which angle, a, b, c or d, is the angle of reflection. … [1] (b) Fig. 9.2 shows a road junction viewed from above. A plane mirror allows the drivers of the two cars A and B to see each other. tall buildings car B tall buildings car A ray of light plane mirror from car A Fig. 9.2 Fig. 9.2 shows a ray of light from car A travelling towards the plane mirror. On Fig. 9.2, carefully continue this ray to show how the driver of car B can see car A. [2] [Total: 4]

4 marks

Mark scheme: 9(a)(i) b B1 9(a)(ii) c B1 9(b) ray from lamp extended to mirror as straight line (by eye) M1 ray reflected to car B A1

This question in 0625/32 Oct/Nov 2021

8 (a) The diagram in Fig. 8.1 shows a ray of light travelling from a glass block into air. ray of light b glass block a c d f air e Fig. 8.1 (i) State the name for the dashed line shown in Fig. 8.1. … [1] (ii) State the letter, a, b, c, d, e or f, which indicates the angle of incidence of the ray in Fig. 8.1. … [1] (iii) State the letter, a, b, c, d, e or f, which indicates the angle of refraction of the ray in Fig. 8.1. … [1] (b) The diagram in Fig. 8.2 shows an object and a thin converging lens. Two rays are drawn from the object to the lens. The points marked F are the principal focuses of the lens. object F F Fig. 8.2 (i) Continue the paths of the two rays in Fig. 8.2 to show how the lens forms an image of the object. [2] (ii) On Fig. 8.2, draw an arrow to represent the image. [1] (iii) Tick (✓) two rows to indicate the nature of the image formed by the lens in Fig. 8.2. nature of image tick enlarged the same size diminished upright inverted [2] [Total: 8]

8 marks

Mark scheme: 8(a)(i) normal B1 8(a)(ii) b B1 8(a)(iii) e B1 8(b)(i) top ray continued through F on right hand side of lens B1 lower ray continued parallel to principal axis (by eye) B1 8(b)(ii) arrow drawn from where their rays cross to principal axis B1 8(b)(iii) diminished B1 inverted B1

This question in 0625/33 Oct/Nov 2021

7 (a) A student investigates refraction through a parallel- sided glass block. Fig. 7.1 shows a ray of red light travelling from the air through the glass block. line X ray of red light 48° air 61° glass 29° block air Fig. 7.1 (i) Using the information in Fig. 7.1, state the angle of refraction for the ray of red light travelling from air into the glass block. angle of refraction = … ° [1] (ii) Using the information in Fig. 7.1, state the term used for line X. … [1] (b) Fig. 7.2 shows an object OX to the left of a thin converging lens. The principal focus on each side of the lens is labelled F. X O F F Fig. 7.2 (i) Two rays from the top of the object are incident on the lens, as shown in Fig. 7.2. On Fig. 7.2, continue the paths of these two rays to show the position of the image of OX formed by the lens. [2] (ii) Draw the image of OX formed by the lens. [1] [Total: 5]

5 marks

Mark scheme: 7(a)(i) 29(°) B1 7(a)(ii) normal (line) B1 7(b)(i) ray through centre continues in straight line B1 (ray through F) drawn parallel to principal axis B1 7(b)(ii) arrow drawn from principal axis to where rays cross B1

This question in 0625/32 May/June 2022

6 A diver is swimming under water. She uses a torch emitting red light. Fig. 6.1 shows three rays of red light coming from the torch. air water 20° 40° 60° diver torch Fig. 6.1 (a) State the name of the dashed lines in Fig. 6.1. … [1] (b) The critical angle for red light travelling from water into air is 48°. (i) State the meaning of the term critical angle. … … [2] (ii) On Fig. 6.1, draw the path of each ray after it reaches the water–air boundary. [3] [Total: 6]

6 marks

Mark scheme: 6(a) normal(s) B1 6(b)(i) angle of incidence B1 that gives an angle of refraction of 90° B1 6(b)(ii) 20° – emergent ray is refracted in air B1 40° – emergent ray is refracted in air AND greater refraction B1 60° – ray is reflected internally B1

This question in 0625/33 May/June 2022

6 (a) Fig. 6.1 shows a ray of light striking a plane mirror. plane mirror O ray of light B Fig. 6.1 (i) State the name of the dashed line OB in Fig. 6.1. … [1] (ii) On Fig. 6.1, indicate the angle of reflection by drawing an X. [1] (iii) State the law of reflection. … [1] (b) A candle is placed in front of a plane mirror. An image of the candle is formed in the mirror. Circle the words from the list that describe the image of the candle. enlarged diminished same size upside-down upright [2] (c) Fig. 6.2 shows a ray of red light striking one side of a glass prism. air air red light glass Fig. 6.2 (i) On Fig. 6.2, draw a line to indicate the path of the red light travelling through the glass prism and emerging into the air. [2] (ii) Explain why the red light follows the path you have drawn in (c)(i). … [1] [Total: 8]

8 marks

Mark scheme: 6(a)(i) normal (line) B1 6(a)(ii) correct angle clearly indicated B1 6(a)(iii) angle of incidence = angle of reflection B1 6(b) same size B1 upright B1 6(c)(i) single ray with correct refraction in glass B1 emergent ray with correct refraction B1 6(c)(ii) refraction B1

This question in 0625/32 Oct/Nov 2022

5 (a) A student shines a ray of red light towards a large glass prism, as shown in Fig. 5.1. The angles of the prism are 45°, 90° and 45°. The critical angle for the glass is 42°. 45° ray of red light glass prism 45° air Fig. 5.1 On Fig. 5.1: (i) continue the path of the ray in the glass prism to a boundary between glass and air [1] (ii) draw and label the normal at the point your ray hits the boundary between glass and air [1] (iii) continue your ray until it emerges into the air. [2] (b) The spectrum of visible light is made up of seven colours. Fig. 5.2 shows a partially completed spectrum for visible light. red yellow green indigo violet Fig. 5.2 (i) On Fig. 5.2, write the names of the missing colours. [2] (ii) State the property of visible light that increases in the direction of the arrow in Fig. 5.2. … [1] [Total: 7]

7 marks

Mark scheme: 5(a)(i) ray continues normally into glass B1 5(a)(ii) one correct normal seen B1 5(a)(iii) ray is totally internally reflected at a glass / air boundary B1 ray emerging from hypotenuse B1 5(b)(i) orange – between red and yellow B1 blue – between green and indigo B1 5(b)(ii) wavelength B1

This question in 0625/33 Oct/Nov 2022

6 A vertical arrow O is used as an object for a converging lens. Fig. 6.1 shows a ray of light from the object passing through the lens. O P F Fig. 6.1 The point labelled F is a principal focus of the lens. (a) State the name of the distance labelled PF on Fig. 6.1. … [1] (b) On Fig. 6.1, draw another ray that enables you to locate the image of O. [2] (c) Draw an arrow to indicate the image. Label the image I. [1] (d) Circle two words from the list which describe the image I. enlarged diminished same size inverted upright [2] [Total: 6]

6 marks

Mark scheme: 6(a) focal length B1 6(b) paraxial ray to lens B1 ray passes through F B1 OR ray passing through principal focus on lhs paraxial ray on rhs 6(c) labelled inverted arrow from where (their) rays cross to principal axis B1 6(d) diminished B1 inverted B1

This question in 0625/33 Oct/Nov 2022

7 (a) A student places a book in front of a plane mirror. State three characteristics of the image of the book formed by the plane mirror. 1 … 2 … 3 … [3] (b) Visible light is one region of the electromagnetic spectrum. Another region is ultraviolet radiation. (i) Give one use of ultraviolet radiation. … [1] (ii) Give one possible harmful effect of excessive exposure to ultraviolet radiation. … [1] [Total: 5]

5 marks

Mark scheme: 7(a) same size (as object / book) B1 same distance from mirror (as book / object) B1 virtual B1 7(b) (use:) security marking OR detecting fake bank notes OR sterilising water B1 (harmful effect:) damage to surface cells / skin OR eyes OR damage to cells / genes / DNA OR skin cancer B1

This question in 0625/32 Feb/March 2023

7 Fig. 7.1 represents two rays of light striking a thin converging lens. The rays are both parallel to the principal axis. F2 and F1 are the focal points of the lens. principal axis F2 F1 screen Fig. 7.1 (a) On Fig. 7.1, continue the path of each ray beyond the lens as far as the screen. [2] (b) Visible light is a region of the electromagnetic spectrum. State one region of the electromagnetic spectrum which has waves of longer wavelength than waves of visible light. … [1] (c) Gamma rays are another region of the electromagnetic spectrum. (i) Describe one use of gamma rays. … [1] (ii) Describe one harmful effect on people of excessive exposure to gamma rays. … [1] [Total: 5]

5 marks

Mark scheme: 7(a) both rays refracted toward principal axis B1 both rays meet at F1 B1 7(b) infrared (rays / waves) OR microwaves OR radio (waves) B1 7(c)(i) any one from:  sterilising food / water  sterilising (medical) equipment  detection of cancer  treatment of cancer  space telescopes B1 7(c)(ii) mutation (of cells / DNA) OR damage to cells / DNA B1

This question in 0625/31 May/June 2023

6 Fig. 6.1 shows light waves passing from air into a glass block. wavefronts air glass Fig. 6.1 (not to scale) (a) (i) State the name of the process shown in Fig. 6.1 as the wavefronts enter the glass block. … [1] (ii) State two changes in the light waves as they pass from air into glass. 1 … 2 … [2] (b) Fig. 6.2 shows a ray of red light travelling through a glass fibre. The glass fibre is made of solid glass. glass ray of red light air air Fig. 6.2 State and explain how the ray of red light travels through the glass fibre as shown in Fig. 6.2. … … … [3] [Total: 6]

6 marks

Mark scheme: 6(a)(i) refraction B1 6(a)(ii) any two from:  wavelength  speed  direction B2 6(b) total internal reflection B1 (red light) travelling from more dense OR into / towards less dense (medium) B1 incident on surface at an angle / angle of incidence greater than critical angle B1

This question in 0625/32 May/June 2023

7 (a) Students are investigating the refraction of light as it travels from air into glass. Their task is to measure the angle of incidence and the angle of refraction at the surface of the glass block. The students have the equipment shown in Fig. 7.1. pencil 30 cm rule protractor sheet of paper ray box glass block Fig. 7.1 Describe the method for the task. You may draw a diagram as part of your answer. … … … … [4] (b) Fig. 7.2 and Fig. 7.3 show two identical lenses, each forming an image. The images I1 and I2 have different characteristics. I2 O O F F F I1 F Fig. 7.2 Fig. 7.3 One difference in the characteristics of the two images is: diminished enlarged Image I1 is … but image I2 is … . State two more differences in the characteristics of the images: Image I1 is … but image I2 is … . Image I1 is … but image I2 is … . [3] [Total: 7]

7 marks

Mark scheme: 7(a) any four from:  draw round the block (on the paper)  use ray box to shine a ray through block  draw crosses on incident and emergent rays  draw ray through block  draw normals  measure angles between rays and normals B4 7(b) Image I1 is real but image I2 is virtual. Image I1 is inverted but image I2 upright. 4 correct – 3 marks 3 or 2 correct – 2 marks 1 correct – 1 mark if no marks scored but all three or four characteristics named, award 1 mark B3

This question in 0625/33 May/June 2023

7 Fig. 7.1 shows a ray diagram for an object positioned on the principal axis of a thin converging lens. F1 and F2 are the focal points of the lens and C is the centre of the converging lens. object C F2 axis F1 object distance = 25 cm Fig. 7.1 (a) On Fig. 7.1, each small square of the grid represents 1.0 cm. Determine the focal length of the converging lens. focal length = … cm [1] (b) On Fig. 7.1, draw an arrow to show the position of the image formed by the converging lens. [1] (c) State three characteristics of the image formed by the converging lens. 1 … 2 … 3 … [3] [Total: 5]

5 marks

Mark scheme: 7(a) 7 (cm) B1 7(b) arrow drawn (perpendicularly) from principal axis to intersection of rays. B1 7(c) (image is) real B1 inverted B1

This question in 0625/31 Oct/Nov 2023

8 (a) In Fig. 8.1, each diagram illustrates a wave property. Draw a line from each diagram to the correct wave property. waves reflection barrier diffraction dispersion glass refraction ray of red light Fig. 8.1 [2] (b) An object O is placed in front of a converging lens. Fig. 8.2 shows two rays of light from the object passing through the lens. O F X Y Fig. 8.2 (i) State the name of the line XY in Fig. 8.2. … [1] (ii) State the name of the point labelled F in Fig. 8.2. … [1] (iii) On Fig. 8.2, draw an arrow to represent the image of O. [1] (iv) Using a ruler, measure the focal length of the converging lens. focal length = … cm [1] (v) Describe characteristics of the image in Fig. 8.2. Choose words from the list. Tick (3) three boxes. enlarged diminished same size inverted upright virtual real [3] [Total: 9]

9 marks

Mark scheme: 8(a) top diagram ----------- diffraction B1 bottom diagram ---------- refraction B1 8(b)(i) principal axis B1 8(b)(ii) principal focus B1 8(b)(iii) vertical line from point where rays cross to the principal axis B1 8(b)(iv) 1.9 (cm) B1 8(b)(v) B1 enlarged ✓ B1 diminished B1 same size inverted ✓ upright virtual real ✓

This question in 0625/32 Oct/Nov 2023

6 (a) A student shines a ray of red light into a rectangular glass block, as shown in Fig. 6.1. ray of red light … ray … ray air … ray glass block Fig. 6.1 (i) Draw the normal at the point where the ray of red light enters the glass block. [1] (ii) On Fig. 6.1, label each ray using words from the list. diffracted diffused dispersed incident reflected refracted [2] (b) Fig. 6.2 and Fig. 6.3 each show two parallel rays of light travelling through air towards a lens. For each lens, draw the path of the two rays as they pass through the lens and back into the air. Fig. 6.2 Fig. 6.3 [2] (c) State the seven colours of visible light. Give the colours in order of frequency. frequency colour greatest smallest [2] [Total: 7]

7 marks

Mark scheme: 6(a)(i) normal correctly drawn B1 6(a)(ii) incident (ray) reflected (ray) B2 refracted (ray) 6(b) Fig. 6.2. – emerging rays converge B1 Fig. 6.3. – emerging rays diverge B1 6(c) all 7 colours named M1 greatest frequency violet AND in correct order (VIBGYOR) A1

This question in 0625/33 Oct/Nov 2023

7 Fig. 7.1 represents an object placed close to a thin converging lens. The scale for the grid is shown. object focal focal point point 5 cm 5 cm Fig. 7.1 (a) (i) Determine the focal length of the converging lens. Use the information in Fig. 7.1. focal length = … cm [2] (ii) On Fig. 7.1, determine the position of the image formed by the lens, by continuing the path of each ray beyond the lens. Use an arrow to indicate the position of the image. [3] (b) Fig. 7.2 shows the regions of the electromagnetic spectrum. infrared ultraviolet gamma radio waves microwaves visible light light light … rays Fig. 7.2 (i) In Fig. 7.2, one region is unlabelled. State the name of the unlabelled region. … [1] (ii) Describe one use of ultraviolet light. … [1] (iii) Describe one harmful effect on people due to excessive exposure to ultraviolet light. … [1] [Total: 8]

8 marks

Mark scheme: 7(a)(i) 10 (cm) A2 (focal length =) 2  5 (C1) 7(a)(ii) ray continued in straight line through centre of lens B1 ray parallel to axis continued to pass through focal point B1 (top of) image position indicated as where rays cross B1 7(b)(i) X-rays B1 7(b)(ii) security marker OR detecting fake bank notes OR sterilising food / water B1 7(b)(iii) damage to (surface) cells / skin / eyes B1 OR (leading to) cancer / eye conditions

This question in 0625/32 Feb/March 2024

7 (a) Fig. 7.1 shows a ray of light striking a plane mirror. The ray is reflected as shown. plane mirror ray of light normal Fig. 7.1 The angle of incidence for the ray of light is 40°. (i) Indicate the angle of reflection by drawing a letter R on Fig. 7.1. [1] (ii) State the size of the angle of reflection in Fig. 7.1. angle of reflection = … ° [1] (b) An object O is placed to the left of a thin converging lens. F1 is the principal focus on one side of the lens and F2 is the principal focus on the other side of the lens. Two rays from the top of the object are incident on the lens, as shown in Fig. 7.2. O F1 F2 thin converging lens Fig. 7.2 (i) On Fig. 7.2, locate the image of O by continuing the path of each ray. [2] (ii) Draw an arrow to represent the image of O. [1] (c) Fig. 7.3 shows a prism producing a spectrum of colours from a narrow beam of white light. prism X narrow beam of white light spectrum of seven colours Z Fig. 7.3 (i) The prism refracts the white light. State the name of the effect that produces a spectrum. … [1] (ii) In the spectrum shown in Fig. 7.3, there are seven colours. List the seven colours in the order they appear between X and Z. X … … … … … … Z … [2] [Total: 8]

8 marks

Mark scheme: 7(a)(i) angle of reflection identified B1 7(a)(ii) 40 (°) B1 7(b)(i) horizontal ray drawn to continue through F2 B1 ray to centre drawn to continue undeviated B1 7(b)(ii) (image drawn / identified) where rays cross B1 7(c)(i) dispersion B1 7(c)(ii) all 7 colours AND in correct order A2 6 of the seven colours given (C1)

This question in 0625/31 May/June 2024

7 (a) Fig. 7.1 shows a ray of red light incident on a glass prism at point P. The ray of red light is refracted at point P. P ray of red light air air glass Fig. 7.1 On Fig. 7.1: (i) draw the normal at point P [1] (ii) draw the path of the ray of red light through the glass prism and into the air. [2] (b) A ray of blue light replaces the ray of red light. The angle of incidence for the blue ray entering the prism is the same as in Fig. 7.1. Describe any difference between the path of the blue ray in the prism and the path of the red ray in the prism. … … [1] (c) Another ray enters the glass prism and is totally internally reflected. State two conditions for a ray to be totally internally reflected. 1 … … 2 … … [2] [Total: 6]

6 marks

Mark scheme: 7(a)(i) correct normal B1 7(a)(ii) ray in glass refracted towards the normal B1 ray in air refracted away from the normal B1 7(b) greater refraction / smaller angle of refraction (at air–glass boundary) B1 7(c) (ray of light) travelling from glass to air B1 angle of incidence greater than critical angle B1

This question in 0625/33 May/June 2024

8 (a) Fig. 8.1 shows a ray diagram for a thin converging lens. The lens forms an image of the object. The object is positioned 30 cm from the centre of the lens. 30 cm 8.0 cm 3.0 cm object image Fig. 8.1 (not to scale) (i) Determine the distance of the image from the centre of the lens. Use information from Fig. 8.1. image distance = … m [1] (ii) Determine the focal length of the lens. Use information from Fig. 8.1. focal length = … m [1] (iii) State two characteristics of the image formed by the lens in Fig. 8.1. 1 … 2 … [2] (b) Fig. 8.2 shows labels for part of the electromagnetic spectrum in order of decreasing wavelength. visible light ultraviolet … … decreasing wavelength Fig. 8.2 (i) Complete Fig. 8.2 by writing the name of one type of radiation in each box. [2] (ii) State one use of ultraviolet radiation. … [1] (iii) State one danger to people from excessive exposure to ultraviolet radiation. … [1] [Total: 8]

8 marks

Mark scheme: 8(a)(i) 0.11 (m) B1 8(a)(ii) 0.08 (m) B1 8(a)(iii) any two from: B2 • diminished OR smaller • inverted OR upside down • real 8(b)(i) X (–rays) (box on left) B1 gamma (rays / radiation) (box on right) B1 8(b)(ii) security marker OR detecting fake bank notes OR sterilising (medical instruments / water / food) B1 8(b)(iii) damage to skin OR (surface) cells OR eyes B1

This question in 0625/31 Oct/Nov 2024

7 (a) Fig. 7.1 represents a ray of red light entering one side of a glass block. glass block air air ray of red light Fig. 7.1 On Fig. 7.1 draw the path of the ray of red light through the glass block and into the air. [2] (b) Fig. 7.2 represents the dispersion of white light by a glass prism. air air white light red light violet light glass prism Fig. 7.2 Two of the colours of the visible spectrum are shown in Fig. 7.2. State the other five colours of the visible spectrum in the correct order. red … … … … … violet [1] (c) Fig. 7.3 represents the regions of the electromagnetic spectrum. infrared gamma radio waves microwaves visible light X-rays waves rays Fig. 7.3 (i) In Fig. 7.3, one region is unlabelled. State the name of the unlabelled region. … [1] (ii) Describe one use of gamma rays. … [1] (iii) Describe one harmful effect on people of excessive exposure to gamma rays. … [1] [Total: 6]

6 marks

Mark scheme: 7(a) ray refracted toward normal as it enters glass (by eye) B1 ray refracted away from normal on leaving glass (by eye) B1 OR emergent ray parallel with incident ray (by eye) 7(b) orange B1 yellow green blue indigo 7(c)(i) ultraviolet (rays / light) B1 7(c)(ii) detecting / treating cancer OR sterilising food / medical equipment B1 OR (medical) imaging OR detecting leaks in (underground) pipes 7(c)(iii) mutation or damage to cells / organs / DNA OR cancer B1

This question in 0625/32 Feb/March 2025

6 (a) Fig. 6.1 represents a ray of red light travelling into and through a glass block. line Y point P air glass ray of red light Fig. 6.1 (i) State the name of the dashed line labelled line Y in Fig. 6.1. … [1] (ii) On Fig. 6.1, label the angle of incidence for the ray of red light at point P. Use the letter X. [1] (iii) The ray of red light travels from the glass into the air at point P. On Fig. 6.1, draw the path for the ray of red light after it leaves the glass at point P. [1] (b) Fig. 6.2 represents a converging lens that is forming the image of an object. converging lens object image 25 cm 20 cm 36 cm Fig. 6.2 (not to scale) (i) Use the information on Fig. 6.2 to determine the focal length of the lens. focal length of lens = … cm [1] (ii) State two characteristics of the image in Fig. 6.2. 1 … 2 … [2] [Total: 6]

6 marks

Mark scheme: 6(a)(i) normal B1 6(a)(ii) angle of incidence indicated B1 6(a)(iii) ray refracted away from normal B1 6(b)(i) (focal length of lens =) 20 (cm) B1 6(b)(ii) any two from: B2 • real • inverted OR upside down owtte • diminished OR small(er) owtte

This question in 0625/31 May/June 2025

5 (a) A teacher produces a water wave in a ripple tank. The wavelength of the water wave is 1.2 cm. The speed of the water wave is 18 cm / s. Calculate the frequency of the water wave. frequency = … Hz [3] (b) Fig. 5.1 shows a ray of red light passing through a prism and emerging into the air. ray of red light air glass air Fig. 5.1 (i) State the name of the process shown in Fig. 5.1 that occurs at the boundaries between air and glass. … [1] (ii) A ray of white light replaces the ray of red light, as shown in Fig. 5.2. The ray of white light splits into different colours. screen ray of white light air glass air Fig. 5.2 Draw on Fig. 5.2 to show the dispersion of white light to produce a coloured spectrum on a screen. Label the red and violet (purple) parts of the spectrum. [3] [Total: 7]

7 marks

Mark scheme: 5(a) 15 (Hz) A3 18 ÷ 1.2 C2 (frequency =) speed ÷ wavelength C1 5(b)(i) refraction B1 5(b)(ii) dispersion at air-glass boundary AND rays continue to screen A2 dispersion / ray broadens seen at either boundary C1 red (at top) and violet / purple (at bottom) B1

This question in 0625/32 May/June 2025

5 (a) A teacher produces a water wave in a ripple tank. The wavelength of the water wave is 1.2 cm. The speed of the water wave is 18 cm / s. Calculate the frequency of the water wave. frequency = … Hz [3] (b) Fig. 5.1 shows a ray of red light passing through a prism and emerging into the air. ray of red light air glass air Fig. 5.1 (i) State the name of the process shown in Fig. 5.1 that occurs at the boundaries between air and glass. … [1] (ii) A ray of white light replaces the ray of red light, as shown in Fig. 5.2. The ray of white light splits into different colours. screen ray of white light air glass air Fig. 5.2 Draw on Fig. 5.2 to show the dispersion of white light to produce a coloured spectrum on a screen. Label the red and violet (purple) parts of the spectrum. [3] [Total: 7]

7 marks

Mark scheme: 5(a) 15 (Hz) A3 18 ÷ 1.2 C2 (frequency =) speed ÷ wavelength C1 5(b)(i) refraction B1 5(b)(ii) dispersion at air-glass boundary AND rays continue to screen A2 dispersion / ray broadens seen at either boundary C1 red (at top) and violet / purple (at bottom) B1

This question in 0625/33 May/June 2025

6 Fig. 6.1 shows an object near a converging lens. The diagram also shows the image of the object that is produced by the lens. Y O A object F F image lens Fig. 6.1 (a) State the name of the line labelled Y. … [1] (b) State the name of the points that are labelled F. … [1] (c) The tip of the object is point O. OA shows the path of a ray from the object as it travels to the lens. On Fig. 6.1, draw the path of this ray as it leaves the lens and travels to the image. [1] (d) On Fig. 6.1, locate the tip of the image. Draw the path of another ray from point O, through the lens and to the tip of the image. [2] (e) The image in Fig. 6.1 is enlarged and inverted. State one more characteristic of the image. … [1] [Total: 6]

6 marks

Mark scheme: 6(a) principal axis B1 6(b) principal focus or principal focii or focal point (s) B1 6(c) ray continued through F to top of image B1 6(d) one of the following: M1 • ray from top of object to centre of lens • ray continued to top of image or A1 • ray from top of object through F to lens • horizontal paraxial ray from lens to top of image 6(e) real B1

This question in 0625/32 Oct/Nov 2025

6 Fig. 6.1 shows the path of a ray of visible light travelling from the top of an object and passing through a converging lens. object X Y scale: each square represents 1 cm Fig. 6.1 (a) State what the line XY represents. … [1] (b) Determine the focal length of the converging lens. focal length = … cm [1] (c) On Fig. 6.1, draw another ray from the object. Continue the path of the ray through the lens until it crosses the path of the ray shown in Fig. 6.1. [2] (d) On Fig. 6.1, draw an arrow to represent the image. Label it ‘image’. [2] [Total: 6]

6 marks

Mark scheme: 6(a) principal axis B1 6(b) 8 (.0) (cm) B1 6(c) ray from top of object to centre of lens M1 ray continued in a straight line to cross drawn ray or A1 ray from top of object through principal focus on LHS of lens to the centre of the lens ray continued as a straight paraxial line to cross drawn ray 6(d) upside down (vertical) arrow (labelled image) from principal axis to point where rays cross A2 point where rays cross indicated C1

This question in 0625/33 Oct/Nov 2025