Simple phenomena of magnetism — Paper 4 · IGCSE Physics 0625

8 A bar magnet is made of metal. (a) Suggest a metal from which the bar magnet is made. … [1] (b) Fig. 8.1 shows the bar magnet being inserted into a coil of wire. The N-pole and the S-pole of the bar magnet are marked. movement coil of magnet S N Fig. 8.1 The coil is connected to a galvanometer. (i) Explain why the galvanometer deflects as the bar magnet is being inserted into the coil. … … … … [3] (ii) Explain what determines the direction of the reading on the galvanometer. … … … [2] (c) Describe a method for demagnetising a bar magnet. … … … [2] [Total: 8]

8 marks

Mark scheme: 8(a) Steel/aluminium/nickel/cobalt/alnico/neodymium/ferrite/alcomax B1 8(b)(i) Mention of magnetic field or magnetic flux OR field created by bar magnet B1 (Magnetic) field (lines) of magnet cut by coil OR (magnetic) field (lines) linked with/through/in the coil changes OR(magnetic) flux (through coil) changes B1 e.m.f. induced B1 8(b)(ii) Direction of movement of magnet through the coil OR which pole of magnet enters the coil B1 Direction of induced e.m.f. opposes change producing it OR (coil) end near magnet/left-hand end becomes a N-pole OR (coil) repels magnet (when moved in) B1 8(c) Hammer the magnet M1 repeatedly/until demagnetised/in E/W direction A1 OR Heat the magnet (M1) high temperature/red hot/in E-W direction (A1) OR Place magnet in coil carrying A.C. (M1) Remove magnet from coil OR decrease the current (slowly) to zero (A1) Total: 8

This question in 0625/41 May/June 2017

10 (a) Describe the movement of charge that causes an object to become positively charged. … [1] (b) Fig. 10.1 shows a negatively charged rod held over an uncharged metal sphere. negatively charged rod – – – – – – – – – uncharged metal sphere insulating support Fig. 10.1 (i) On Fig. 10.1, add + and – signs to represent the results of the movement of charge within the sphere. [2] (ii) Describe the actions that must be taken to obtain an even distribution of positive charge on the surface of the sphere. … … … [2] [Total: 5]

5 marks

Mark scheme: 10(a) Electrons/negative charges removed from/flow from/lost (from the object) B1 10(b)(i) At least 3 plus signs in top half of sphere B1 Same number of minus signs in bottom half of sphere B1 OR Excess of plus signs over minus signs in top half of sphere (B1) Equal excess of minus signs over plus signs in bottom half of sphere (B1) 10(b)(ii) (with rod present) connect earth (to sphere) OR touch (sphere) with conductor/finger M1 Remove earth wire and then remove charged rod OR remove conductor/finger and then rod. A1 Total: 5

This question in 0625/41 May/June 2017

10 (a) Fig. 10.1 shows a wire that carries a current into the page. The circles on Fig. 10.1 show the pattern of the magnetic field around the wire. Fig. 10.1 (i) On Fig. 10.1, draw an arrow on each circle to show the direction of the magnetic field. [1] (ii) State why the spacing of the circles increases as the distance from the wire increases. … … [1] (b) Fig. 10.2 shows an electric door lock. The slot in the door contains an unmagnetised iron bolt attached to a spring. The slot in the door frame is empty. This slot is surrounded by the coils of a solenoid. In Fig. 10.2 the door is unlocked. The spring is not stretched. door door frame spring solenoid unmagnetised iron bolt S Fig. 10.2 In Fig. 10.3 the door is locked. The spring is now stretched. Fig. 10.3 The bolt is initially in the position shown in Fig. 10.2. Describe and explain what happens when (i) the switch S is closed, … … … … … [4] (ii) the switch S is reopened. … … … [2]

8 marks

Mark scheme: 10(a)(i) clockwise arrows on at least 3 circles B1 10(a)(ii) (magnetic) field becomes weaker / decreases (as distance from wire increases) B1 10(b)(i) any four from these six: • charge flows OR current in solenoid / wire / circuit • solenoid becomes magnet / magnetised • bolt becomes magnet / magnetised • (such that) unlike poles (of solenoid and bolt are) facing o.w.t.t.e. • bolt is attracted • bolt moves / (door) locks / spring stretched B4 10(b)(ii) solenoid OR bolt no longer magnetised OR bolt no longer attracted B1 (spring contracts and pulls) bolt back / bolt returns (to original position) / (door) unlocked B1

This question in 0625/42 Oct/Nov 2017

9 (a) A student wants to demagnetise a permanent bar magnet. She suggests these steps: 1. Place the magnet in a long coil. 2. Switch on a large alternating current in the coil. 3. Switch off the current. 4. Remove the bar from the coil. State and explain whether the steps will always be able to demagnetise the magnet. … … … … [3] (b) (i) Fig. 9.1 shows a coil supplied with current using a split-ring commutator. coil magnet S split-ring N carbon brush battery Fig. 9.1 State and explain any motion of the coil. … … … … … [3] (ii) The coil in Fig. 9.1 consists of three turns of wire. The magnetic field strength of the magnet is M. With a current of 2.0 A in the coil, the coil experiences a turning effect T. The first row of Table 9.1 shows this data. Table 9.1 magnetic field number of turns current in the coil / A turning effect strength 3 2.0 M T 3 8.0 M 6 2.0 M M 3 2.0 2 Complete Table 9.1 to give the turning effect for the changes made to the arrangement shown in Fig. 9.1. Choose your answers from the box. T T T 8 4 2 T 2T 4T 8T [3] [Total: 9]

9 marks

Mark scheme: 9(a) Would not be effective OR No 1 With current on OR the (alternating) current should not be switched off 1 Magnet should be withdrawn from the coil 1 OR Magnet would be alternately magnetised in different directions (1) Would remain magnetised in the direction occurring at the moment of switching off (1) 9(b)(i) Coil turns 1 Clockwise/continuously 1 Current (in coil) reverses every half turn/when coil is in vertical position OR force on current in a magnetic field 1 9(b)(ii) 1 × (4 × T) 1 2 × (2 × T) 1 3 × (T ÷ 2) 1

This question in 0625/41 May/June 2018

10 (a) An uncharged conducting metal plate rests on insulating supports. Fig. 10.1 shows the plate and a positively charged insulating plastic sheet placed on top of the metal plate. plastic sheet metal plate insulating support insulating support Fig. 10.1 (i) Describe any flow of charge that takes place when the plastic sheet is placed onto the metal plate. … … [1] (ii) On Fig. 10.1, draw how charges are now arranged within the metal plate. [1] (iii) State and explain if this arrangement of charge helps to keep the plastic sheet in place. … … … … [2] (b) Fig. 10.2 shows two uncharged conducting spheres suspended on insulating threads. Fig. 10.2 1. The spheres are now both given positive charges. On Fig. 10.2, draw a possible position of each sphere and thread. 2. Explain the positions you have drawn. … … [2] [Total: 6]

6 marks

Mark scheme: 10(a)(i) electrons/–ve charges (in metal) move o.w.t.t.e. to top half/move up 1 10(a)(ii) more –ve charges in top half than bottom OR more +ve charges in bottom half than top NOT if contradiction e.g. more +ve in top and more –ve in top 1 10(a)(iii) helps (keep plastic sheet in place)/yes 1 unlike charges attract OR attractive force between metal plate and plastic sheet 1 10(b) 1 both threads angled away from other ball 1 2 like/same/positive charges repel 1

This question in 0625/42 May/June 2018

8 (a) (i) Fig. 8.1 shows a positively charged cube of insulating material. The cube is fixed to a piece of wood that is floating on water. A negatively charged rod is held above the piece of wood and brought close to the cube, as shown. positively charged cube of insulating material negatively charged rod – + – + – + piece of wood floating on water Fig. 8.1 State and explain any movement of the piece of wood. … … … … [2] (ii) Fig. 8.2 shows two cubes of insulating material. One is positively charged and the other is negatively charged. The cubes are fixed to a piece of wood that is floating on water. Charged rods are held above the piece of wood and brought close to the cubes, as shown. negatively charged rod negatively charged cube of insulating material – – – + positively charged cube – + of insulating material – + – + + piece of wood floating on water positively charged rod Fig. 8.2 State and explain any movement of the piece of wood. … … … … [2] (b) In terms of a simple electron model, describe the differences between conductors and insulators. conductors … … … insulators … … … [2] (c) On Fig. 8.3, draw the electric field pattern around a single point positive charge. + Fig. 8.3 [1] [Total: 7]

7 marks

Mark scheme: 8(a)(i) (moves) towards negative rod / to right B1 opposite / unlike charges attract B1 8(a)(ii) (wood / it) or cubes( / float) rotates / turns / spins B1 2 forces cause moment / couple / torque / turning effect B1 8(b) conductors: free / delocalised electrons OR electrons move B1 insulators: no free / delocalised electrons OR electrons / charges cannot move OR electrons fixed in place B1 8(c) at least 4 approx. evenly spaced straight lines with correct arrows radially outwards B1

This question in 0625/42 Oct/Nov 2018

9 Fig. 9.1 shows a permanent bar magnet next to a circuit that contains a coil and a galvanometer. N S Q Fig. 9.1 (a) Suggest a metal from which the magnet is made. … [1] (b) The magnet is moved to the left and inserted a small distance into the coil. The galvanometer deflects briefly and shows that there is a current in the coil. (i) Explain why there is a current in the coil. … … … … [2] (ii) As the magnet is moving near to the coil, end Q of the coil behaves as a magnetic pole. State the polarity of end Q and explain why it has this polarity. … … … [2] (c) Suggest two ways in which the deflection of the galvanometer can be reversed. 1. … … 2. … … [2] [Total: 7]

7 marks

Mark scheme: 9(a) B1 9b(i) magnetic field (lines) cut OR changing magnetic field / flux linkage (in coil) B1 e.m.f. / voltage induced B1 9(b)(ii) (end Q) is an N-pole B1 repels / opposes (approaching) N-pole / magnet B1 9(c) any two from: withdraw N-pole (from end Q) OR move magnet to the right insert S-pole (into end Q) insert N-pole into other end withdraw S-pole from other end or carry on past mid-point B2

This question in 0625/42 Oct/Nov 2018

8 (a) A conducting sphere is mounted on an insulating stand. Explain how you would use a positively charged rod of insulating material to charge the sphere by induction. … … … … … [3] (b) Fig. 8.1 shows an electronic component. Fig. 8.1 State the name of the component shown in Fig. 8.1 … [1] (c) In the space below, write down the truth table for a NAND gate. [2] (d) Fig. 8.2 shows the connections to two logic gates. A D B E C Fig. 8.2 Table 8.1 shows part of the truth table for the arrangement of logic gates in Fig. 8.2. Complete Table 8.1 for the input values shown. Table 8.1 intermediate inputs output point A B C D E 0 0 1 0 1 1 1 1 0 1 1 1 [3] [Total: 9]

9 marks

Mark scheme: 8(a) bring (charged) rod close to sphere / touching sphere B1 earth sphere or equivalent B1 remove earth (connection) AND keep rod close to sphere (until earth removed) o.w.t.t.e. B1 8(b) light emitting diode OR LED B1 8(c) correct labelling of I/P and O/P, all I/P numbers correct in any order B1 all 4 rows of numbers correct, in any order B1 8(d) column D correct B1 1st two rows of E correct B1 2nd two rows of E correct B1

This question in 0625/42 May/June 2019

9 (a) Describe how to demagnetise a bar magnet using alternating current (a.c.) in a coil. … … … … [3] (b) Fig. 9.1 shows a simple direct current (d.c.) motor. d.c. power supply split-ring commutator N S coil Fig. 9.1 (i) Explain the purpose of the split-ring commutator. … … … … [3] (ii) The voltage of the power supply is increased. State the effect this has on the motor. … [1] [Total: 7]

7 marks

Mark scheme: 9(a) place magnet in coil B1 EITHER (gradually) withdraw magnet« B1 «with ac (in coil) switched on B1 OR reduce current« (B1) «to zero (B1) 9(b)(i) keeps coil rotating (in the same direction) o.w.t.t.e. B1 by changing direction of current (in the coil) B1 every half cycle/180 degrees B1 9(b)(ii) (coil rotates) faster B1

This question in 0625/42 May/June 2019

7 (a) A permanent magnet is made from only one material. Underline the material from which it is possible to make a permanent magnet. [1] aluminium copper soft iron mercury plastic steel uranium (b) An electron source produces a narrow beam of electrons that all travel at the same speed. The electron source is placed in a vacuum and the beam of electrons travels vertically downwards. Fig. 7.1 shows the beam of electrons before it passes between the N-pole and the S-pole of a magnet. electron source beam of electrons N-pole S-pole Fig. 7.1 (i) Describe what is meant by the direction of a magnetic field. State the direction of the magnetic field between the two poles in Fig. 7.1. … … … [1] (ii) Describe and explain what happens to the beam of electrons in the magnetic field between the poles of the magnet in Fig. 7.1. … … … … [3] (c) A beam consists of α-particles, β-particles and γ-rays. Explain how a uniform magnetic field may be used to separate the α-particles, the β-particles and the γ-rays. … … … … [3] [Total: 8]

8 marks

Mark scheme: 7(a) steel (underlined) B1 7(b)(i) the direction of the force on a N-pole and left to right / N to S B1 7(b)(ii) beam deflects B1 beam deflects into the page B1 moving electrons / charges constitute a current or left-hand rule or moving electrons / current in a magnetic field experiences a force B1 7(b) (part of) beam deflects B1 α-particles deflect in opposite / different direction to β-particles / electrons or all α-particles have similar deflections or α- particles deflect less B1 γ-rays do not deflect B1

This question in 0625/41 Oct/Nov 2020

9 (a) Fig. 9.1 shows a bar magnet and four plotting compasses A, B, C and D. D C A bar magnet B Fig. 9.1 On Fig. 9.1: (i) draw an arrow on each of the three plotting compasses B, C and D to show the direction of the magnetic field [2] (ii) label the magnetic poles of the bar magnet N and S. [1] (b) Describe one method for demagnetising a bar magnet. … … … … [2] (c) Fig. 9.2 represents a current in a wire. The current is into the plane of the paper. (i) Draw the pattern of the magnetic field produced around the wire. Show clearly the direction of the magnetic field. Fig. 9.2 [2] (ii) The direction of the current in the wire is reversed. The magnitude of the current is unchanged. State the effect that reversing the current has on the magnetic field produced. … … [1] [Total: 8]

8 marks

Mark scheme: 9(a)(i) C pointing horizontally to right B1 B AND D pointing horizontally to left B1 9(a)(ii) S on left AND N on right B1 9(b) any one of the following methods: 1 heat magnet C1 to high temperature / red hot A1 2 hammer the magnet (B1) repeatedly / in E–W direction (B1) 3 (place) magnet in a coil / solenoid carrying a.c. (M1) remove magnet from coil OR decrease current (slowly) to zero (A1) 9(c)(i) at least 3 concentric circles B1 closer together near the wire AND clockwise arrow B1 9(c)(ii) arrows OR field reverses / is in opposite direction B1

This question in 0625/42 Oct/Nov 2020

7 (a) Fig. 7.1 shows two magnets and the gap between the N pole of one magnet and the S pole of the other magnet. N S N S Fig. 7.1 On Fig. 7.1, draw three lines to show the pattern and direction of the magnetic field in the gap. [2] (b) (i) Fig. 7.2 is a repeat of Fig. 7.1 showing the two magnets. On Fig. 7.2, draw the position of a plotting compass needle when it comes to rest in the gap between the N pole and the S pole. N S N S Fig. 7.2 [1] (ii) Explain why the needle comes to rest in this position. … … … [2] (c) Describe a method of demagnetising a bar magnet. … … … [2] [Total: 7]

7 marks

Mark scheme: 7(a) 3 lines from N face to S face middle line must be straight AND perpendicular to end faces B1 at least 1 arrow from N to S AND NO arrows from S to N B1 7(b)(i) needle perpendicular to end faces AND {arrow pointing to S OR correctly labelled N OR S} B1 7(b)(ii) compass / needle / it aligns with field OR compass / needle / it points in direction of magnetic field OR compass / needle / it points to S(outh) B1 N pole of needle attracted to S of magnet(s) OR N pole repelled by N of magnets OR unlike poles attract / like poles repel B1 7(c) heat OR hammer B1 with magnet lying (magnetically ) E – W B1 OR place in coil / solenoid with a.c. (M1) withdraw OR reduce current to 0 (A1)

This question in 0625/42 May/June 2021

7 A plastic rod becomes negatively charged when it is rubbed with a woollen cloth. (a) Describe, in terms of particles, how the rod becomes negatively charged when rubbed with the cloth. … … … [2] (b) A light, conducting ball is at rest on a metal table. When the rod is brought close to the ball, as shown in Fig. 7.1, the ball jumps up towards the rod. rod ball metal table Fig. 7.1 (i) Explain why the ball jumps up. … … … … [3] (ii) The ball touches the rod and falls back down to the table. Explain why this happens. … … … [2] [Total: 7]

7 marks

Mark scheme: 7(a) electrons mentioned B1 negative charges / electrons move from cloth or move to rod B1 7(b)(i) electrons / negative charge(s) repelled to earth or ball charged by induction B1 ball positively charged B1 opposite charges attract B1 7(b)(ii) negatively charged (by rod) or ball discharges / becomes neutral B1 repelled by rod or pulled down by gravity / its weight B1

This question in 0625/41 Oct/Nov 2021

8 (a) Fig. 8.1 shows a conducting object A, initially uncharged, held on an insulating stand. The positively charged rod B is brought close to object A. conducting charged rod B + object A + + + insulating stand + Fig. 8.1 (i) On Fig. 8.1, draw the distribution of charges on object A. [2] (ii) A wire is connected from object A to earth. State and explain any movement of charge. statement … explanation … … … [2] (b) There is a current in a wire of 0.65 mA for 2.2 minutes. Calculate the charge that flows. charge = … [3] [Total: 7]

7 marks

Mark scheme: 8(a)(i) clearly more –ve (than +ve) on left AND more +ve (than –ve) on right B1 same number of +ve and - ve B1 8(a)(ii) -ve charges (flow) from earth OR -ve charges flow to object B1 electrons flow to balance (excess) +ve charge on the object B1 8(b) I = Q / t in any form OR (Q =) It C1 (Q =) 0.65 × 10–3 × 2.2 × 60 C1 (Q =) 0.086 C A1

This question in 0625/42 Oct/Nov 2021

7 Fig. 7.1 shows a small plotting compass which is aligned with the magnetic field between magnetic poles A and B of a U-shaped magnet. A B S N Fig. 7.1 (a) State the polarity of the poles. pole A … pole B … [1] (b) Fig. 7.2 shows a wire, placed between two poles, carrying a current in the direction of the arrow. S N Fig. 7.2 On Fig. 7.2, draw an arrow to show the direction of the force on the wire due to the magnetic field. [2] (c) Fig. 7.3 shows a β-particle moving in the direction of the arrow between the same two poles. S β -particle N direction of travel of β-particle when in the position shown Fig. 7.3 On Fig. 7.3, draw an arrow to show the direction of the force on the β-particle due to the magnetic field. [2] [Total: 5]

5 marks

Mark scheme: 7(a) (pole A:) N AND (pole B:) S B1 7(b) vertical B1 up B1 7(c) vertical B1 down B1

This question in 0625/42 May/June 2022

11 (a) Fig. 11.1 shows a solenoid connected to a battery. solenoid battery Fig. 11.1 On Fig. 11.1, draw the pattern of the magnetic field inside and around the solenoid. Indicate the direction of the magnetic field with an arrow. [3] (b) Electrical power is transmitted at a voltage of 400 kV. A transformer reduces the voltage to 33 kV for use by heavy industry in large factories. The number of turns on the primary coil of the transformer is 11 000. Calculate the number of turns on the secondary coil of the transformer. number of turns = … [2] [Total: 5]

5 marks

Mark scheme: 11(a) at least one line on the left and one line on the right, outside coil B1 AND curved back over the top and under the base of the coil, towards the central core of the coil at least two (straight vertical) lines inside coil B1 direction of arrow correct on at least one line and none wrong B1 11(b) 910 A2 NP / NS = VP / VS OR (NS =) (VS / VP)  NP C1 11000  33 000 11000  33 OR (NS =) OR (NS =) 400 000 400

This question in 0625/43 Oct/Nov 2022

8 (a) (i) State what is meant by a magnetic field. … … [1] (ii) Define the direction of a magnetic field. … … [1] (b) Fig. 8.1 shows a negatively charged metal sphere. – – – – – – – – Fig. 8.1 On Fig. 8.1, draw four lines to show the electric field and its direction. [2] (c) Fig. 8.2 shows a circuit. V R3 R1 R2 Fig. 8.2 The three cells are identical and have zero resistance. The resistors R1, R2 and R3 are identical. The reading on the voltmeter is 6.0 V. When the diode is conducting, it has zero resistance and zero potential difference (p.d.) across it. (i) Determine the e.m.f. of one cell. e.m.f. = … [1] (ii) Determine the ratio of the p.d. across R2 to the p.d. across R3. … [1] (iii) All the cells are reversed. 1. State and explain the change in current in R1. … … [1] 2. Determine the new value of the ratio of the p.d. across R2 to the p.d. across R3. … [1] [Total: 8]

8 marks

Mark scheme: 8(a)(i) region in which a (magnetic) pole experiences a force B1 8(a)(ii) in the direction of the force on the N pole B1 Question Answer Marks 8(b) 4 radial lines outside sphere, touching the sphere and equally spaced all around sphere B1 direction of arrows towards the sphere B1 8(c)(i) 2.0 V A1 8(c)(ii) (ratio of p.d. across R2 : R3 =) 1 : 2 B1 8(c)(iii)1. current is zero in R1 AND diode is in wrong direction (to allow current) owtte B1 8(c)(iii)2. (ratio of p.d. across R2 : R3 =) 1 : 1 B1

This question in 0625/42 May/June 2023

8 (a) Fig. 8.1 shows a wire carrying a large current. large current square card Fig. 8.1 (i) Fig. 8.2 shows the square card viewed from above. card Fig. 8.2 On Fig. 8.2, draw three magnetic field lines that indicate the direction of the magnetic field and how its strength varies with distance from the wire. [3] (ii) The current in the wire increases and the direction of the current is reversed. State how these changes affect the magnetic field. … … [2] (b) Electricity is transmitted at high voltage. Explain why a high voltage increases the efficiency of transmission even with thinner wires. … … … … [3] [Total: 8]

8 marks

Mark scheme: 8(a)(i) three concentric circles centred on X B1 second and third circles further apart than first and second circles B1 direction of arrows clockwise B1 8(a)(ii) strength of magnetic field increases B1 its direction reverses B1 8(b) any three from: B3 • P = I 2R OR power (loss) = I 2R • (high voltage allows) low current (so at same power output, less power / energy lost) • thin wires have high resistance (so more power / energy lost) • (low) current has a greater effect (on efficiency) than (high) resistance (of the thin wires)

This question in 0625/42 Feb/March 2024

7 (a) Fig. 7.1 shows three bars of steel, A, B and C. A B C Fig. 7.1 A student is given the three pieces of steel. Two of the pieces are magnetised and one piece is unmagnetised. Describe and explain how the student determines which piece is unmagnetised using only the three pieces of steel. … … … … … … … … [4] (b) Fig. 7.2 shows a circuit diagram of a step‑down transformer. output Fig. 7.2 (i) The mains voltage supplied to the transformer is 240 V. The output power of the transformer is 45 W. The transformer is 100% efficient. Calculate the input current to the transformer. input current = … [3] (ii) Draw a labelled diagram of a step‑down transformer. On the labels, state a suitable material for each of the components. [3] [Total: 10]

10 marks

Mark scheme: 7(a) (end of) one piece of steel brought close to (the end of) another piece owtte B1 look to see if there is repulsion/attraction AND test between different ends/poles owtte B1 any two from:  repeat a valid test between the other pieces  only magnets repel each other OR the pieces that repel are magnets  attractions at both ends indicates one of them is unmagnetised OR the piece that only attracts is unmagnetised OR the piece that does not repel (at both ends) is unmagnetised B2 7(b)(i) 0.19 A A3 Ip Vp = Is Vs OR (Ip =) Is Vs / Vp OR (Ip =) 45 / 240 OR Ip Vp = 45 OR power in primary = power in secondary C1 (Ip= ) 45 / 240 C1 7(b)(ii) labelled diagram showing:  (soft) iron core  copper (coils)  primary and secondary (coils) labelled AND fewer coils on secondary than on primary B3

This question in 0625/42 May/June 2024

7 A solid bar is inside a copper solenoid. Fig. 7.1 shows that the copper solenoid is connected in series with a battery and a variable resistor. copper solenoid bar Fig. 7.1 The device shown in Fig. 7.1 is an electromagnet. (a) Suggest a suitable material for the bar. … [1] (b) The right-hand end of the bar is the S pole. (i) Fig. 7.2 shows the bar viewed from above. On Fig. 7.2, draw at least six field lines to show the pattern and direction of the magnetic field surrounding the bar. S Fig. 7.2 [3] (ii) The resistance of the variable resistor increases. Explain what happens to the magnetic field surrounding the bar and state how the pattern of field lines that represents the field changes. … … … … [3] (c) A square coil of many turns is placed close to the bar. Fig. 7.3 shows the plane of the square coil parallel to the flat circular surface at the right-hand end of the bar. terminals copper solenoid square coil bar Fig. 7.3 The resistance of the variable resistor is alternately increased and decreased. Explain what happens in the wires of the square coil. … … … … [3] [Total: 10]

10 marks

Mark scheme: 7(a) (soft) iron B1 7(b)(i) (at least) one complete field line between the poles of the bar (either above or below the bar) B1 no crossing AND attempt at correct shape AND at least six lines from / to poles B1 at least one arrowhead towards S pole B1 7(b)(ii) current (in the coil) decreases B1 (current decreases so magnetic field) strength decreases B1 (field strength decreases so) fewer field lines (in same area) OR (field strength decreases so) field lines further apart B1 7(c) Any two from: B2 1 (changing resistance causes) changing current (through solenoid) 2 (changing current causes) changing magnetic field (around solenoid) 3 (square) coil cuts (changing) magnetic field OR coil in changing magnetic field e.m.f. induced (between terminals) B1

This question in 0625/41 Oct/Nov 2024

6 Fig. 6.1 shows a person using a magnetic window cleaner. The part on the outside of the window is attracted to the inside part through the glass window. Fig. 6.1 Each part of the window cleaner contains two magnets. Fig. 6.2 shows the magnetic field between the parts of the window cleaner. handle bar magnets bar magnets inside window outside window Fig. 6.2 (a) Glass is not a magnetic material. State the difference between magnetic and non-magnetic materials. … … [1] (b) Suggest a suitable material for the magnets in the window cleaner. Explain your answer. … … [1] (c) Label the poles of the magnets in Fig. 6.2. [1] (d) State how the field lines in Fig. 6.2 show different strengths of the magnetic field between the magnets. … … [1] [Total: 4]

4 marks

Mark scheme: 6(a) any one from: B1 • magnetic materials are attracted to magnets • non-magnetic materials are not attracted to magnets • magnetic materials experience a force in magnetic fields • non-magnetic materials don’t experience a force in magnetic fields 6(b) any one from: B1 • steel as it stays magnetised • steel makes a permanent magnet 6(c) N and S poles correctly labelled B1 braille: north to south owtte 6(d) field lines close(r) indicates strong(er) (magnetic) field owtte ORA B1

This question in 0625/41 May/June 2025

8 (a) State what is meant by a magnetic field. … … [1] (b) Fig. 8.1 shows an ammeter connected to a coil wound on a thin plastic cylinder. A small trolley is placed on a curved track which passes through the cylinder. A trolley cylinder S N track Fig. 8.1 The trolley is released from the position shown in Fig. 8.1. It travels through the coil from right to left. The trolley travels back from left to right. It has a lower maximum speed when it travels from left to right. The plastic cylinder does not affect any magnetic field. A magnet is fixed to the trolley. (i) State why there is a lower maximum speed when the trolley travels back from left to right. … … [1] (ii) Fig. 8.2 shows a close‑up view of the ammeter. 0 Fig. 8.2 As the trolley enters the coil moving from right to left, the ammeter needle deflects to the left and then returns to zero. State and explain any changes to the deflection on the ammeter as the trolley enters the coil when moving back from left to right. … … … … … … [3] [Total: 5]

5 marks

Mark scheme: 8(a) region in which a (magnetic) pole experiences a force B1 8(b)(i) friction between trolley and track OR the (induced) current produces a magnetic field which opposes the (magnetic) field B1 that causes the (induced) current 8(b)(ii) any three from: B3 • direction will (still) be left OR there is no change of direction • induced current / emf / voltage does not change direction • smaller deflection • smaller (rate of) change of magnetic field • smaller current / emf / voltage induced (in coil)

This question in 0625/42 Oct/Nov 2025