Cambridge IGCSE Physics 0625 — 2011 Oct/Nov Paper 2 · Variant 1

This document consists of 15 printed pages and 1 blank page. DC (CW/CGW) 34004/4 © UCLES 2011 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education * 1 2 6 4 5 3 7 1 3 4 * PHYSICS 0625/21 Paper 2 Core October/November 2011 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. You may lose marks if you do not show your working or if you do not use appropriate units. Take the weight of 1 kg to be 10 N (i.e. acceleration of free fall = 10 m / s2). At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. www.XtremePapers.com

2 0625/21/O/N/11 © UCLES 2011 1 Fig. 1.1 shows the speed-time graph of a moving object. B A 5 00 10 20 35 time / s speed m / s C D Fig. 1.1 (a) Which part, or parts, of Fig. 1.1 indicate when the object is (i) travelling at uniform speed, …[1] (ii) accelerating? …[1] (b) Calculate the distance travelled in the last 15 s. distance = … m [3] [Total: 5]

3 0625/21/O/N/11 © UCLES 2011 [Turn over 2 Two girls attempt to measure the speed of the water in a river, as shown in Fig. 2.1. bridge 1 bridge 2 50 m Fig. 2.1 (a) The distance between the two bridges is measured as 50 m. Suggest an appropriate instrument that they might use to measure this distance. …[1] (b) The girl on bridge 1 drops a piece of wood into the water. The girl on bridge 2 measures how long it takes for the piece of wood to reach bridge 2. It takes 400 s to travel between the two bridges. (i) Name an appropriate instrument that could be used to measure this time. …[1] (ii) Describe the procedure for measuring this time. … … … … …[3] (iii) Calculate the speed of the water. speed = …[4] [Total: 9]

4 0625/21/O/N/11 © UCLES 2011 3 (a) In a laboratory experiment to find the centre of mass of a triangular piece of card, the card is suspended first from point A and then from point B, as shown in Figs. 3.1 and 3.2. A B D E C C D B A E Fig. 3.1 Fig. 3.2 When suspended from A, point D is found to be vertically below A. When suspended from B, point E is vertically below B. (i) What piece of apparatus might be used to determine the vertical lines through A and B? …[1] (ii) On Fig. 3.3 below, draw construction lines to find the position of the centre of mass of the triangular card. Label this point clearly with the letter G. C D B A E [3] Fig. 3.3

5 0625/21/O/N/11 © UCLES 2011 [Turn over (b) Fig. 3.4 illustrates a toy that always returns to the upright position, whatever position it is put in to start with. Fig. 3.4 On one of the three positions of the toy shown in Fig. 4.3, clearly mark X at a possible position for the centre of mass of the toy. [2] [Total: 6]

6 0625/21/O/N/11 © UCLES 2011 4 In Fig. 4.1, the smoke cell consists of an illuminated glass box into which some smoke has been injected. microscope smoke cell light Fig. 4.1 (a) Describe briefly what is seen when the contents of the smoke cell are viewed through the focused microscope. … … … …[3] (b) State the name we normally give to what is seen. …[1] (c) What deductions about the properties and behaviour of air molecules can be made from these observations? … … … …[3] [Total: 7]

7 0625/21/O/N/11 © UCLES 2011 [Turn over 5 A card is held against a rotating toothed wheel, as shown in Fig. 5.1. card Fig. 5.1 The wheel has 150 teeth and rotates 3 times per second. (a) Calculate the frequency of the sound produced. frequency = … Hz [2] (b) State the approximate range of frequencies that can be heard by a healthy human ear. lowest frequency = … Hz highest frequency = … Hz [1] (c) The speed of rotation of the wheel is increased. What happens, if anything, to the pitch of the sound that is heard? …[1] [Total: 4]

8 0625/21/O/N/11 © UCLES 2011 6 The list below contains the names of the various regions of the electromagnetic spectrum, but they are in the wrong order and an extra, non-electromagnetic type of wave motion has been included. infra-red radiation X-rays gamma rays visible light radio waves ultrasound waves ultra-violet radiation (a) Which one of these is not electromagnetic? …[1] (b) (i) In the boxes below, list the various regions of the electromagnetic spectrum in order of wavelength. The first and last boxes have been filled in for you. radio waves gamma rays [2] (ii) Which of these has the longest wavelength? …[1] (iii) Which of these produces a significant heating effect? …[1] (iv) Which of these may be used to obtain a picture of a broken bone inside the body? …[1] [Total: 6]

9 0625/21/O/N/11 © UCLES 2011 [Turn over 7 The pivoted steel arrow from a small compass has become demagnetised. The coil shown in Fig. 7.1 is to be used to magnetise it again. coil steel arrow Fig. 7.1 (a) Describe carefully (i) how the coil is used to magnetise the steel arrow, … … … … …[3] (ii) how the polarity of the magnetised needle may be checked. … … … …[1] (b) On Fig. 7.1, draw the magnetic field pattern of the magnetised needle. [2] [Total: 6]

10 0625/21/O/N/11 © UCLES 2011 8 A student learning about electric circuits connects up the circuit shown in Fig. 8.1. battery ammeter coil of wire variable resistor (rheostat) 2 1 0 3 AMPS 4 5 Fig. 8.1 (a) The student has already made one mistake with his connections. What is his mistake? …[1] (b) In the space below, draw the circuit diagram of the arrangement shown in Fig. 8.1, using standard symbols. [2] (c) The student now connects a voltmeter to the circuit, so that readings can be taken to find the resistance of the coil of wire. On your circuit diagram, draw the voltmeter, connected to measure the potential difference across the coil. [1]

11 0625/21/O/N/11 © UCLES 2011 [Turn over (d) Having obtained a correctly-working circuit, the readings on the two meters for one setting of the variable resistor are as shown in Figs. 8.2 and 8.3. AMPS 0 5 1 4 2 3 VOLTS 0 5 10 15 Fig. 8.2 Fig. 8.3 (i) Record these two readings. ammeter reading = … A voltmeter reading = … V [1] (ii) The slider on the variable resistor (see Fig. 8.1) is moved a small distance to the left, reducing its resistance. State what happens to the readings on the two meters. ammeter reading … voltmeter reading …[2] (iii) The slider is adjusted so that the total resistance in the circuit is double that which gave the readings in Figs. 8.2 and 8.3. Calculate the new values of the readings on the meters. ammeter reading = … A voltmeter reading = … V [2] [Total: 9]

12 0625/21/O/N/11 © UCLES 2011 9 (a) The circuit symbol shown in Fig. 9.1 represents a device often used in electrical equipment. Fig. 9.1 State the name of this device. …[1] (b) Fig. 9.2 shows, in simplified form, the essential parts of a grid system for distributing electrical energy from a power station to domestic consumers. The device in part (a) is used both at X and at Y. power station X 22 000 V 132 000 V transmission cables and pylons 240 V domestic consumer Y Fig. 9.2 (i) Using information from Fig. 9.2, deduce the ratio secondary turns primary turns necessary at X and at Y. turns ratio at X = … turns ratio at Y = …[3] (ii) State two reasons why power transmission is cheaper if the voltage across the cables is very high. 1. … … 2. … …[2] [Total: 6]

13 0625/21/O/N/11 © UCLES 2011 [Turn over 10 (a) Complete the following statement about an electric field. An electric field is a region in which … experiences a … [2] (b) Fig. 10.1 shows two identical light uncharged balls suspended on thin nylon threads. nylon thread ball B A Fig. 10.1 Ball A is given a positive charge and ball B is given a negative charge. In the space below, draw a diagram showing the positions that the balls and threads will take, now that the balls are charged. [2] (c) On ball B in your diagram, use labelled arrows to show the directions of (i) the electrostatic force on the ball (label it E), (ii) the weight of the ball (label it W), (iii) the tension force of the thread on the ball (label it T). [2] (d) Ball B is in equilibrium. State the value of the resultant of forces E, W and T. resultant = …[1] [Total: 7]

14 0625/21/O/N/11 © UCLES 2011 11 Fig. 11.1 shows a tube that can be used to produce cathode rays. Metal plates above and below the tube have zero potential difference between them. Fig. 11.1 (a) On Fig. 11.1, clearly label (i) the filament cathode (label it C), (ii) the anode (label it A). [2] (b) On Fig. 11.1, draw (i) a battery (label it B), connected to cause thermionic emission of electrons, (ii) a 1000 V power supply (label it P), connected to cause a beam of cathode rays along the tube, (iii) the path of the beam of cathode rays along the tube. [3] (c) What is seen when the beam of cathode rays hits the screen? … …[1] (d) A high potential difference is now connected between the two metal plates, so that the lower plate is positive and the upper plate is negative. What change is seen on the screen? … …[1] [Total: 7]

15 0625/21/O/N/11 © UCLES 2011 12 The count-rate from a sample of radioactive material is investigated by a team of scientists in a laboratory. (a) With the radioactive sample in place, the count-rate from the sample is determined every 7 days, with the results shown below. The background count-rate has already been subtracted. time / days 0 7 14 21 28 count-rate counts / s 1000 550 300 160 90 On Fig. 12.1, plot a graph of count-rate from the sample against time. [3] 0 200 0 5 10 15 time / days 20 25 30 400 600 count-rate counts / s 800 1000 Fig. 12.1 (b) (i) From your graph, find the time at which the count-rate is 1. 800 counts / s, … days 2. 200 counts / s. … days [2] (ii) From the figures in (b)(i), find the value of the half-life of the substance. half-life = … days [3] [Total: 8]

16 0625/21/O/N/11 © UCLES 2011 BLANK PAGE Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 2011 question paper for the guidance of teachers 0625 PHYSICS 0625/21 Paper 2 (Core Theory), maximum raw mark 80 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination. • Cambridge will not enter into discussions or correspondence in connection with these mark schemes. Cambridge is publishing the mark schemes for the October/November 2011 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses. www.XtremePapers.com

Page 2 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0625 21 © University of Cambridge International Examinations 2011 NOTES ABOUT MARK SCHEME SYMBOLS & OTHER MATTERS B marks are independent marks, which do not depend on any other marks. For a B mark to be scored, the point to which it refers must actually be seen in the candidate's answer. M marks are method marks upon which accuracy marks (A marks) later depend. For an M mark to be scored, the point to which it refers must be seen in a candidate's answer. If a candidate fails to score a particular M mark, then none of the dependent A marks can be scored. C marks are compensatory method marks which can be scored even if the points to which they refer are not written down by the candidate, provided subsequent working gives evidence that they must have known it. e.g. if an equation carries a C mark and the candidate does not write down the actual equation but does correct working which shows he knew the equation, then the C mark is scored. A marks are accuracy or answer marks which either depend on an M mark, or which are one of the ways which allow a C mark to be scored. c.a.o. means "correct answer only". e.c.f. means "error carried forward". This indicates that if a candidate has made an earlier mistake and has carried his incorrect value forward to subsequent stages of working, he may be given marks indicated by e.c.f. provided his subsequent working is correct, bearing in mind his earlier mistake. This prevents a candidate being penalised more than once for a particular mistake, but only applies to marks annotated "e.c.f." e.e.o.o. means "each error or omission". brackets ( ) around words or units in the mark scheme are intended to indicate wording used to clarify the mark scheme, but the marks do not depend on seeing the words or units in brackets. e.g. 10 (J) means that the mark is scored for 10, regardless of the unit given. underlining indicates that this must be seen in the answer offered, or something very similar. OR/or indicates alternative answers, any one of which is satisfactory for scoring the marks. Spelling Be generous about spelling and use of English. If an answer can be understood to mean what we want, give credit. Significant Answers are acceptable to any number of significant figures ≥ 2, except if figures specified otherwise, or if only 1 sig. fig. is appropriate. Units Incorrect units are not penalised, except where specified. More commonly, marks are allocated for specific units. Fractions These are only acceptable where specified. Extras Ignore extras in answers if they are irrelevant; if they contradict an otherwise correct response or are forbidden by mark scheme, use right + wrong = 0 Ignore Indicates that something which is not correct is disregarded and does not cause a right plus wrong penalty.

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0625 21 © University of Cambridge International Examinations 2011 Not/NOT Indicates that an incorrect answer is not to be disregarded, but cancels another otherwise correct alternative offered by the candidate i.e. right plus wrong penalty applies.

Page 4 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0625 21 © University of Cambridge International Examinations 2011 1 (a) (i) BC B1 (ii) AB B1 (b) area under graph C1 0.5 × 15 × 5 C1 37.5 (m) A1 [5] 2 (a) tape measure OR trundle wheel OR laser measure IGNORE metre rule B1 (b) (i) clock OR watch (any sort) B1 (ii) set clock/watch to zero OR note start time OR start clock/watch/timing B1 (start clock/watch/timing) when wood seen to fall or equivalent B1 stop clock/watch/note time when wood reaches bridge 2 B1 (iii) speed = distance/ time in any form, letters, words, numbers C1 50/400 C1 0.125 A1 m/s B1 [9] 3 (a) (i) plumb-line (name or description) OR try-square and (horiz.) bench OR spirit level B1 (ii) line joining A and D M1 line joining B and E M1 intersection clearly labelled G (dependent on scoring both M marks) A1 (b) X clearly on centre line B1 X clearly within semicircular portion, but not on surface B1 [6] 4 (a) dark specks OR bright specks NOT molecules/particles B1 moving C1 randomly/zigzag OR dancing about A1 (b) Brownian motion/movement B1 (c) invisible/too small to see/very small B1 moving fast/high kinetic energy B1 moving randomly/all directions B1 [7] 5 (a) 150 × 3 C1 450 (Hz) A1

Page 5 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0625 21 © University of Cambridge International Examinations 2011 (b) any figure between 20 and 50 inclusive AND any figure between 15,000 and 25,000 inclusive B1 (c) increases/rises B1 [4] 6 (a) ultrasound B1 (b) (i) infra-red visible all 4 correct B2 ultra-violet (any 2 correct B1) X-rays (ii) radio OR the top/first one B1 (iii) infra-red B1 (iv) X-rays OR gamma rays B1 [6] 7 (a) (i) needle inside coil B1 current through coil OR connect battery/power supply M1 direct current OR d.c. OR a.c. and switch off before removing needle/ magnet A1 (ii) freely suspend/pivot and see which end points N (or equivalent) OR see which end is repelled by N pole of a magnet B1 (b) 4+ smooth curves leaving one end and going to the other (ignore any arrows) B1 no lines crossing or meeting, even at ends B1 [6] 8 (a) battery/ammeter connected wrong way round OR negative of battery should go to negative of ammeter B1 (b) correct symbols for battery, ammeter and rheostat (allow common variants on battery/cell symbol) M1 all components in series A1 (c) voltmeter (any recognisable symbol) clearly in parallel with coil B1 (d) (i) 2.8 (A) and 12 (V) both B1 (ii) ammeter increases B1 voltmeter increases B1 (iii) 1.4 (A) OR half candidate’s original reading B1 6 (V) OR half candidate’s original reading B1 [9]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0625 21 © University of Cambridge International Examinations 2011 9 (a) transformer (ignore step-up/down) B1 (b) 132,000/22,000 OR 240/132,000 C1 X: 6 A1 Y: 0.001818 to at least 4 dec. pl. OR 1/550 NOT 550 A1 (c) less heat/energy loss thinner/smaller cables less copper used less cable weight any 2 use ✓ +  = 0 for incorrect extras B1+B1 less massive pylons cheaper smaller current [6] 10 (a) (electric) charge OR charged body B1 force B1 (b) A and B closer together allow touching M1 threads straight and equal angle (by eye) to vertical A1 (c) E horizontal to left W vertically down all 3 marked on his diagram –1 e.e.o.o. B2 T up thread (d) zero or 0 or nothing B1 [7] 11 (a) (i) filament/cathode clearly and correctly labelled B1 (ii) anode clearly and correctly labelled B1 (b) (i) battery shown connected across filament (no e.c.f.) B1 (ii) power supply connected between filament & anode (no e.c.f.) B1 (iii) straight path shown along axis (no e.c.f.) B1 (c) bright spot (or equivalent) B1 (d) spot moves down B1 [7] 12 (a) points correctly plotted (±½ small square) –1 e.e.o.o. B2 smooth curve through candidate’s points (by eye) B1

Page 7 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0625 21 © University of Cambridge International Examinations 2011 (b) (i) 1. in range 2.2–3.0 B1 2. in range 18.0–19.0 B1 (ii) 2 half-lives C1 (candidate’s 2 – candidate’s 1)/2 C1 7.5–8.6 (days) e.c.f. A1 [8]