Electrical quantities — Paper 4 · IGCSE Physics 0625

9 Fig. 9.1 shows a graph of current against potential difference (p.d.) for a filament lamp. 0.80 current / A 0.60 0.40 0.20 0 0 2.0 4.0 6.0 8.0 p.d. / V Fig. 9.1 (a) State what happens to the resistance of the filament of the lamp as the p.d. changes (i) from 0 V to 1.0 V, … [1] (ii) from 1.0 V to 8.0 V. … [1] (b) At normal brightness, the p.d. across the lamp is 8.0 V. Calculate, for normal brightness, (i) the resistance of the lamp, resistance = … [3] (ii) the power of the lamp. power = … [2] (c) Five of these lamps, operating at normal brightness, are connected in parallel to a power supply. power supply Fig. 9.2 Determine (i) the electromotive force (e.m.f.) of the power supply, e.m.f. = … [1] (ii) the current from the power supply. current = … [1] [Total: 9]

9 marks

Mark scheme: 9(a)(i) Resistance constant B1 9(a)(ii) Resistance increases B1 9(b)(i) I = V/R in any form OR (R=) V/I C1 8.0/0.72 C1 11 Ω A1 9(b)(ii) (P = ) IV OR 0.72 × 8.0 C1 5.8 W A1 OR I2R OR 0.722 × candidate’s (b)(i) OR V2/R OR 82 / candidate’s (b)(i) (C1) 5.7 W or 5.8 W (dependent on exact data used) (A1) 9(c)(i) 8.0 V B1 9(c)(ii) (5 × 0.72 =) 3.6 A B1 Total: 9

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10 (a) Describe, in terms of particles and the terminals of the battery, the movement of charge in an electric circuit. … … [2] (b) Fig. 10.1 shows a lightning flash between a cloud and the ground beneath. cloud lightning flash ground Fig. 10.1 The charge built up on the cloud before the lightning flash is 0.60 C. This charge is completely transferred to the ground by the lightning flash in 5.0 × 10–5 s (0.000050 s). (i) Calculate the current between the cloud and the ground. current = … [2] (ii) The potential difference (p.d.) between the cloud and the ground during the lightning flash is 2.5 × 108 V. Calculate the energy transferred during the lightning flash. energy = … [2] (iii) Suggest what happens to the energy calculated in (b)(ii). … … [1] [Total: 7]

7 marks

Mark scheme: 10(a) Electrons / negative particles B1 Move (in circuit) from negative (terminal) to positive (terminal of battery) B1 10(b)(i) (I =) Q / t OR 0.60 / 0.000050 C1 12 000 A A1 10(b)(ii) (E=) I V t OR 12 000 × 2.5 × 108 × 0.000050 C1 1.5 × 108 J A1 OR (E=) Q V OR 0.60 × 2.5 × 108 (C1) 1.5 × 108 J (A1) 10(b)(iii) Converted to any two of: thermal energy / heat, light and sound B1 Total: 7

This question in 0625/42 Feb/March 2017

9 A 12 V battery is connected in series to a 24 W lamp and to a parallel pair of identical resistors X and Y. Fig. 9.1 is the circuit diagram. 12 V X A B Y Fig. 9.1 The 24 W lamp lights at normal brightness when the potential difference (p.d.) across it is 6.0 V. The lamp is at normal brightness. (a) Calculate the resistance of the lamp. resistance = … [3] (b) Determine (i) the p.d. between A and B, p.d. = … [1] (ii) the combined resistance of the parallel pair of identical resistors X and Y, resistance = … [1] (iii) the resistance of X. resistance = … [2] (c) Resistor X is removed from the circuit in Fig 9.1. Explain why the lamp becomes dimmer. … … … … [2] [Total: 9]

9 marks

Mark scheme: 9(a) (I =) P I C1 6.0 ÷ 4.0 C1 1.5 Ω A1 9(b)(i) 6.0 V B1 9(b)(ii) 1.5 Ω B1 9(b)(iii) 1 2 1 1 1 R R R = + OR 1 ÷ 1.5 = 1 2 1 1 R R + OR 1 ÷ 1.5 = 2 R C1 3.0 (Ω) A1 9(c) resistance of circuit/parallel pair increases B1 current (in lamp) decreases OR less p.d. across lamp B1 Total: 9

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8 (a) Fig. 8.1 shows an uncharged conducting sphere on an insulating stand placed close to a positively charged rod. positively + + charged rod + + + conducting sphere + insulating stand Fig. 8.1 The rod and the sphere are not moved. Describe how to charge the sphere using a wire connected to earth and explain whether the sphere becomes positively charged or negatively charged. … … … … [3] (b) Fig. 8.2 shows a small black circle that represents a positive charge. On Fig. 8.2, draw the pattern and the direction of the electric field in the region around the charge. [2] Fig. 8.2 (c) A charge of 7.0 C flows along a wire in 5.0 minutes. Calculate the current in the wire. current = … [2] [Total: 7]

7 marks

Mark scheme: 8(a) touch the sphere with the earth wire B1 negatively charged and electrons flow to sphere B1 remove earth wire or electrons / negative charges attracted (by rod) B1 8(b) four or more straight, radial lines and uniformly spaced B1 at least one arrow outwards and no wrong arrows B1 8(c) (I =) Q / t or 7.0 / (5.0 × 60) or 7.0 / 5.0 or 1.4 (A) C1 0.023(3333) A A1

This question in 0625/43 Oct/Nov 2017

7 (a) State, in terms of their structure, why metals are good conductors of electricity. … … [1] (b) A cylindrical metal wire W1, of length l and cross-sectional area A, has a resistance of 16 Ω. l A second cylindrical wire W2 having length 2 and cross-sectional area 2 A, is made from the same metal. Determine (i) the resistance of W2, resistance of W2 = … [2] (ii) the effective resistance of W1 and W2 when connected in parallel. resistance of parallel pair = … [2] (c) The parallel pair of resistors in (b)(ii) is connected to a battery that is made from three cells in series, each of electromotive force (e.m.f.) E. There is a current in each resistor. (i) State the e.m.f. of the battery. … [1] (ii) The current in the battery is IB, the current in W1 is I1 and the current in W2 is I2. Place a tick (3) in one box to indicate how these three currents are related. I1 > I2 > IB I1 > IB > I2 I2 > I1 > IB I2 > IB > I1 IB > I1 > I2 IB > I2 > I1 I1 = I2 = IB [1] [Total: 7]

7 marks

Mark scheme: 7(a) (Metals) contain free/mobile electrons/delocalised electrons 1 7(b)(i) R α L and R α 1 ÷ A OR R α L ÷ A OR R = 16 × ½ ÷ 2 OR R = 16 ÷ 4 1 4.0 Ω 1 7(b)(ii) 1 ÷ R = (1 ÷ R1) + (1 ÷ R2) OR R = (R1 × R2) ÷ (R1 + R2) OR (1 ÷ R) = (1 ÷ 4) + (1 ÷ 16) OR (4 × 16) ÷ (4 + 16) 1 3.2 Ω 1 7(c)(i) 3E or 3 × E 1 7(c)(ii) IB > I2 > I1 (6th box ticked) 1

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9 Fig. 9.1 shows a circuit that includes a battery of electromotive force (e.m.f.) 12 V. 12 V A V 20 Ω Fig. 9.1 The reading on the ammeter is 0.15 A. (a) Calculate the resistance of the circuit. resistance = … [2] (b) The variable resistor is adjusted so that its resistance decreases. (i) State what happens to the reading on the ammeter. … [1] (ii) State and explain what happens to the reading on the voltmeter. … … … [2] (c) The battery is formed from cells of electromotive force (e.m.f.) 1.5 V. (i) Explain, in terms of electrical energy, what is meant by an electromotive force (e.m.f.) of 1.5 V. … … [2] (ii) State how many 1.5 V cells are connected in series to form the battery. … [1] [Total: 8]

8 marks

Mark scheme: 9(a) (R =) V ÷ I OR 12 ÷ 0.15 C1 80 Ω A1 9(b)(i) increases B1 9(b)(ii) (voltmeter reading) decreases OR less p.d. across variable resistor B1 more p.d. across 20Ω/fixed resistor B1 9(c)(i) 1.5 J of (electrical) energy supplied in driving charge around the circuit B1 energy per unit charge OR per coulomb B1 9(c)(ii) 8 B1

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9 Fig. 9.1 shows the symbol for a 12 V battery. 12 V Fig. 9.1 (a) Two lamps are connected in parallel with the battery. On Fig. 9.1, using the correct symbols, complete the circuit diagram. [1] (b) One of these lamps has a resistance of 6.0 Ω. Calculate, for this lamp: (i) the current current = … [1] (ii) the power. power = … [2] (c) The power of the other lamp is 36 W. Calculate the total energy delivered to this lamp in 20 hours. energy = … [3] [Total: 7]

7 marks

Mark scheme: 9(a) 2 lamps with correct circuit symbol, in parallel, with correct connection to battery B1 9(b)(i) (12 / 6.0 =) 2.0 A B1 9(b)(ii) (P =) IV OR 2.0 × 12 C1 OR (P =) I2R OR 2.02 × 6.0 (C1) OR (P =) V2 / R OR 122 / 6.0 (C1) 24 W A1 9(c) (E =) IVt OR Pt in any form OR 36 × 20 C1 = 36 × 20 × 60 × 60 C1 = 2.6 × 106 J A1

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7 A defibrillator is a machine that sends an electrical charge through the heart of a patient whose heart is not beating correctly. Doctors learn to use a defibrillator by practising on a medical dummy. Fig. 7.1 shows the two contacts of a defibrillator attached to a medical dummy. contacts defibrillator medical dummy Fig. 7.1 The contacts that touch the dummy are made from metal, and when the defibrillator is being used, one contact becomes strongly negatively charged and the other contact becomes strongly positively charged. The handles of the contacts are made from plastic, which is an electrical insulator. (a) (i) State how the structure of an electrical insulator differs from the structure of a conductor. … … [1] (ii) Suggest why the handles are made from an electrical insulator. … … … [2] (b) Explain, in terms of the particles involved, how one contact becomes negatively charged and how the other contact becomes positively charged. … … … [2] (c) The defibrillator passes a charge of 9.1 × 10–3 C through the medical dummy in 6.5 × 10–4 s. Calculate the average current in the dummy. current = … [2] [Total: 7]

7 marks

Mark scheme: 7(a)(i) no delocalised / free / mobile electrons in an insulator or electrons fixed (in place) / tightly bound in an insulator B1 7(a)(ii) no charge flows / current in doctor or doctor does not receive an electric shock B1 which might prove fatal / kill / injure / harm doctor or so charge flows / current in patient B1 7(b) electrons move (from one contact to the other) B1 negative contact gains electrons / negative charges and positive contact loses electrons / negative charges B1 7(c) (I =) Q / t or 9.1 × 10–3 / 6.5 × 10–4 C1 14 A A1

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8 A 9.0 V battery is connected to a 120 Ω resistor in series with wire P. Fig. 8.1 shows a voltmeter connected across the 120 Ω resistor. 9.0 V 120 Ω P V Fig. 8.1 (a) State the energy changes that are taking place in the circuit. … … … [2] (b) The reading on the voltmeter is 2.4 V. Calculate: (i) the current in the 120 Ω resistor current = … [2] (ii) the potential difference (p.d.) across wire P p.d. = … [1] (iii) the resistance of wire P. resistance = … [1] (c) Wire P has a diameter d and a length l. A second piece of wire Q is made of the same material as P. The diameter of wire Q is 0.50 × d and its length is 5.0 × l. Calculate the resistance of wire Q. resistance = … [4] [Total: 10]

10 marks

Mark scheme: 8(a) from chemical (energy) to thermal / heat (energy) C1 from chemical (energy) to thermal / heat (energy) and as a result of electrical working A1 8(b)(i) (I =) V / R or 2.4 / 120 C1 0.020 A A1 8(b)(ii) 6.6 V B1 8(b)(iii) 330 Ω B1 8(c) multiplication by 5.0 or R ∝ l C1 multiplication by 2.0 / 4.0 or division by 0.50 / 0.25 or R ∝ 1 / A or R ∝ 1 / r 2 C1 multiplication by 4.0 or division by 0.25 or 20 × 330 C1 6600 Ω A1

This question in 0625/43 Oct/Nov 2018

9 (a) Describe how a direct current (d.c.) differs from an alternating current (a.c.). … … [1] (b) Fig. 9.1 shows how the voltage output of an a.c. generator varies with time. 8.0 voltage / V 6.0 4.0 2.0 0 0 0.20.2 0.40.4 0.60.6 0.80.8 1.01.0 1.21.2 timetime // ss –2.0 –4.0 –6.0 –8.0 Fig. 9.1 A heater is connected directly to the a.c. generator and the maximum current in the heater is 0.75 A. (i) On Fig. 9.2, sketch a graph to indicate how the current in the heater varies with time. 1.00 current / A 0.75 0.50 0.25 0 0 0.20.2 0.40.4 0.60.6 0.80.8 1.01.0 1.21.2 timetime // ss –0.25 –0.50 –0.75 –1.00 [1] Fig. 9.2 (ii) Calculate the power produced by the heater when the current is 0.75 A. power = … [2] (c) Fig. 9.3 shows the coil ABCD of the a.c. generator between two magnetic poles. rotation direction B C N A D S Fig. 9.3 (i) On Fig. 9.3, draw a straight arrow to indicate the direction in which side AB of the coil is moving. Label this arrow M. [1] (ii) Deduce the direction of the current induced in side AB of the coil and explain your reasoning. … … … … [2] (iii) The rate at which the coil of the a.c. generator rotates increases. State two ways in which the alternating voltage changes. 1. … … 2. … … [2] [Total: 9]

9 marks

Mark scheme: 9(a) (a d.c. has) constant value / magnitude or direction does not change or has only one direction B1 9(b)(i) sinusoidal curve in phase with voltage and maximum value of 0.75 A and same frequency B1 9(b)(ii) (P =) VI or 7.2 × 0.75 C1 5.4 W A1 9(c)(i) vertical, upward arrow labelled M on side AB B1 9(c)(ii) A to B and (Fleming’s) right-hand rule (in some way) B1 rule explained (i.e. fingers explained or labelled 3D diagram) B1 9(c)(iii) greater (maximum) voltage B1 greater frequency or smaller time period or changes direction more often or alternates faster B1

This question in 0625/43 Oct/Nov 2018

9 Fig. 9.1 shows current-potential difference (p.d.) graphs for a resistor and for a thermistor. 6.0 current / A 4.0 resistor 2.0 thermistor 0 0 2.0 4.0 6.0 8.0 p.d. / V Fig. 9.1 (a) Calculate the resistance of the thermistor when the p.d. across it is 7.0 V. resistance = … [2] (b) In Table 9.1, tick the boxes that indicate the effect on the resistances of the resistor and of the thermistor when the p.d. across them is increased from 0 to 7.0 V. Table 9.1 component resistance increases resistance is constant resistance decreases resistor thermistor [2] (c) The thermistor and the resistor are connected in parallel to a 7.0 V supply. Calculate: (i) the current from the supply current = … [2] (ii) the energy transferred from the supply in 5.0 minutes. energy = … [2] [Total: 8]

8 marks

Mark scheme: 9(a) C1 1.5 Ω A1 9(b) Resistor: resistance is constant B1 Thermistor: resistance decreases B1 9(c)(i) 4.6 + 4.6 C1 9.2 A A1 OR Combined resistance = (1.522 / (1.52 + 1.52) = ) 0.76 Ω (C1) (I = ) 7.0 / 0.76 = 9.2 A (A1) 9(c)(ii) (E =) IVt OR in words OR 9.2 × 7 × 5 × 60 C1 19 000 J A1

This question in 0625/42 Feb/March 2019

10 Fig. 10.1 shows a circuit containing a filament lamp of resistance 0.30 Ω and two resistors, each of resistance 0.20 Ω. 0.20 Ω 0.20 Ω 0.30Ω Fig. 10.1 (a) Calculate the combined resistance of the lamp and the two resistors. resistance = … [3] (b) The potential difference (p.d.) of the supply is increased so that the current in the lamp increases. State and explain any change in the resistance of the lamp. Statement … Explanation … … [2] [Total: 5]

5 marks

Mark scheme: 10(a) C1 (Rp = ) 0.12 (Ω) C1 (Rt = 0.12 Ω + 0.20 Ω = ) 0.32 Ω A1 10(b) Statement : resistance of lamp increases M1 Explanation : temperature of lamp increases A1

This question in 0625/42 May/June 2019

8 Fig. 8.1 shows a 240 V mains supply connected to an air‑conditioning unit and a freezer. A fuse X is placed in the circuit as shown. X 240 V air-conditioning mains freezer unit supply Fig. 8.1 The freezer has an operating power of 700 W. (a) Calculate the current in the freezer. current = … [2] (b) The maximum operating current of the air‑conditioning unit is 7.5 A. Fuses of current rating 1 A, 3 A, 5 A, 10 A, 13 A and 30 A are available. Suggest a suitable rating for fuse X. Give two reasons for your answer. fuse rating … Reason 1 … … … Reason 2 … … … [3] (c) A fuse is made out of a short length of wire. Explain why fuses of a higher rating are made of thicker wire. … … … … … [3] (d) Electrical energy can be obtained from renewable and non‑renewable sources of energy. (i) State two renewable sources of energy. Source 1 … Source 2 … [2] (ii) State one social, economic or environmental disadvantage of one of your answers to (d)(i). … … … [1] [Total: 11]

11 marks

Mark scheme: 8(a) C1 I (= 700 240 ) = 2.9 A A1 8(b) 13 A fuse B1 any two out of: 2.9 + 7.5 SEEN if too low it would break / blow / melt when the appliances are operating normally if fuse too high wouldn’t break / blow until current was too high which would be dangerous (to people /wires /appliance) B2 8(c) (Resistance inversely proportional to area so) resistance of thicker wire is lower B1 Fuse will melt at higher current B1 because heating effect = I 2 R OR less heating effect (for same current) owtte B1 8(d)(i) Any two renewable sources of energy from: solar, wind, water, hydroelectric, waves, tidal, geothermal B2 8(d)(ii) Any relevant disadvantage for one of their correct answers to (d)(i) e.g.: Energy for wind / waves / Sun not always available Cost of building wind turbines or tidal barrages or hydroelectric dams Wind turbines affect the scenery of some areas Solar (farms) use (agricultural) land / takes up a lot of space B1

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9 (a) Fig. 9.1 shows an electrical component. Fig. 9.1 State the name of the component shown in Fig. 9.1. … [1] (b) In the space below, write down the truth table for a NOR gate. [2] (c) Fig. 9.2 shows the connections between two logic gates. A D B E C Fig. 9.2 Complete the truth table shown in Table 9.1 for this combination of logic gates. Table 9.1 inputs intermediate output point A B C D E 0 1 1 1 0 1 1 1 0 1 1 1 [3] (d) Referring to a simple electron model, state what distinguishes electrical conductors from electrical insulators. … … … … [1] [Total: 7]

7 marks

Mark scheme: 9(a) light dependent resistor OR LDR B1 9(b) Input 1 Input 2 Output 0 0 1 0 1 0 1 0 0 1 1 0 2 input columns and one output column AND 4 correct rows of input B1 All 4 rows with correct, in any order B1 9(c) D E 1 1 1 1 0 0 0 1 all D correct B1 first 2 rows of E correct B1 last 2 rows of E correct B1 9(d) conductors have free / delocalised electrons / electrons which move (freely) (electrons in insulators don’t move or are fixed) B1

This question in 0625/43 May/June 2019

5 Fig. 5.1 shows a sphere that is negatively charged. The sphere is attached to a plastic stand. plastic stand Fig. 5.1 (a) On Fig. 5.1, draw arrows to indicate the pattern and direction of the electric field in the region surrounding the sphere. [2] (b) A smaller, uncharged metal sphere S is suspended by a plastic thread and brought close to the negatively charged sphere. Fig. 5.2 shows the two spheres. plastic thread S Fig. 5.2 (i) By drawing on Fig. 5.2, indicate the distribution of charge on S. [2] (ii) State what happens to S. … … [1] (iii) An earth wire is then touched against S. Describe what happens in the wire and state how this affects the charge on S. … … … [2] (c) The metal sphere S is an electrical conductor. The plastic thread is an electrical insulator. Explain this difference by referring to the structures of the two materials. … … … [2] [Total: 9]

9 marks

Mark scheme: 5(a) four or more radial arrows / lines outside surface at least one arrow pointing towards (centre of) sphere and none wrong B1 B1 5(b)(i) positive charges on left and negative charges on right of S equal numbers M1 A1 5(b)(ii) it moves towards / attracted towards the negatively charged sphere / to the left B1 5(b)(iii) electrons / negative charges move (along the wire) towards Earth / towards ground / down the wire S becomes positively charged B1 B1 5(c) electrons mentioned free (to move) / delocalised / mobile in metals / S or fixed in position in plastic / stand M1 A1

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6 Fig. 6.1 shows a shower that takes in cold water. The water passes through an electric water heater and emerges from the showerhead at a higher temperature. showerhead electric water heater Fig. 6.1 The power of the heater is 9000 W. (a) The shower is powered by a 230 V electricity supply. (i) Calculate the current in the heater when it is switched on. current = … [2] (ii) Suggest a suitable rating for the fuse in the heater circuit. fuse rating = … [1] (b) The specific heat capacity of water is 4200 J / (kg °C). The initial temperature of the cold water is 16 °C. Determine the maximum mass of water that can be heated to a temperature of 35 °C in 1.0 s. mass = … [4] (c) A safety control in the shower switches off the shower when the water becomes dangerously hot. The control uses a thermocouple thermometer to measure the temperature of the heated water. (i) Describe the structure of a thermocouple thermometer. Include a diagram in your answer. … … … [2] (ii) Suggest one reason why a thermocouple thermometer is suitable for this purpose. … … [1] [Total: 10]

10 marks

Mark scheme: 6(a)(i) 39 A C1 A1 6(a)(ii) 40 A or any greater integer value (in A) up to and including 60 A B1 6(b) E = Pt or in any form words, symbols or numbers or (E =) Pt or 9000 × 1.0 or 9000 J seen 35 – 16 or 19 (°C) seen m = E /(c∆T) or in any form words, symbols or numbers or (m =) E /(c∆T) or 9000 / (4200 × 19) 0.11 kg C1 C1 C1 A1 6(c)(i) two different metal wiresjoined at one end and voltmeter between free ends or three metal wires and two different joined ABA and voltmeter between free ends B1 B1 6(c)(ii) any one from: quick response / makes measurements fast measures rapidly varying temperatures electrical output small heat capacity robust / rugged B1

This question in 0625/41 Oct/Nov 2019

7 The resistance of a 1.0 m length of resistance wire is 7.6 Ω. A length of this wire is taped to a metre rule. A crocodile clip is connected to one end of the resistance wire exactly at the 0 m mark of the rule. Fig. 7.1 shows the crocodile clip connected to terminal P. 0 m mark movable contact metre rule l 1.0 m mark 0 crocodile clip resistance wire connecting wire terminal P terminal Q Fig. 7.1 A second terminal Q is connected to a movable contact using a long length of connecting wire. The movable contact is in contact with the resistance wire at a length l from the 0 m mark on the rule. The movable contact is placed at different points on the resistance wire. The resistance R of the length l of the wire depends on l. (a) On Fig. 7.2, sketch a graph to show how R varies with l for values of l between l = 0 and l = 1.0 m. Mark appropriate values on the axes of the graph. R / Ω 0 0 l / m Fig. 7.2 [2] (b) Fig. 7.3 shows a battery of electromotive force (e.m.f.) 12 V connected across the 1.0 m length of the resistance wire. 12 V l movable contact metre rule resistance wire terminal P terminal Q Fig. 7.3 (i) State what is meant by electromotive force (e.m.f.). … … … [2] (ii) Calculate: 1. the current in the resistance wire current = … [2] 2. the potential difference (p.d.) between terminal P and terminal Q when l = 0.35 m p.d. = … [1] 3. the charge that passes through the resistance wire in 5.5 minutes. charge = … [2] [Total: 9]

9 marks

Mark scheme: 7(a) 7 / 7.6 / 8 / 10 marked towards top of y-axis and 1(.0) towards right of x-axis a straight line of positive gradient from 0, 0 to point 1.0, 7.6 B1 B1 7(b)(i) energy (transferred) per unit charge energy (transferred) from chemical or energy (transferred) to electrical or energy (transferred) around / in a (complete) circuit B1 B1 7(b)(ii) 1. I = V / R or in any form words, symbols or numbers or (I =) V / R or 12 / 7.6 1.6 A C1 A1 2. 4.2 V or 4.3 V B1 3. Q = It or in any form words, symbols or numbers or (Q =) It or 1.6 × 5.5 × 60 or 1.6 × 5.5 or 8.8 (C) 520 C or 530 C C1 A1

This question in 0625/41 Oct/Nov 2019

8 (a) Fig. 8.1 shows a negatively charged conducting sphere. − − − − − − − − Fig. 8.1 On Fig. 8.1, draw the electric field pattern around the sphere. [2] (b) The current in an electrical device is 0.21 A. Calculate the charge that flows during a 75 s period of time. charge = … [2] [Total: 4]

4 marks

Mark scheme: 8(a) radial lines from sphere B1 arrows pointing towards sphere B1 8(b) Q = It, in any form OR 0.21 × 75 C1 16 C A1

This question in 0625/43 Oct/Nov 2019

7 An electromagnet consists of a solenoid X that is made of copper wire. The solenoid contains an iron core. (a) Explain why: (i) the structure of copper makes it a suitable material for the wire … … … [2] (ii) iron is a suitable material for the core of an electromagnet. … … … [2] (b) Fig. 7.1 shows the electromagnet inside a second solenoid Y. terminals of Y solenoid X iron core solenoid Y a.c. power supply Fig. 7.1 (i) Describe and explain what happens in solenoid Y when solenoid X is connected to an alternating current (a.c.) power supply. … … … … [3] (ii) A switch and a lamp are connected in series with the terminals of solenoid Y. When the switch is closed, the lamp lights up at normal brightness. Describe and explain what happens to the current in solenoid X when the switch is closed. … … … [2] [Total: 9]

9 marks

Mark scheme: 7(a)(i) (copper) contains free electrons B1 good electrical conductor B1 7(a)(ii) magnetic material OR easily magnetised B1 temporary magnetic material OR easily demagnetised B1 7(b)(i) alternating / changing / varying magnetic field (produced by X) B1 (electromagnetic) induction in Y B1 (alternating) electromotive force (e.m.f.) between terminals of Y / in Y B1 7(b)(ii) current in X increases B1 to supply the power used in Y / the lamp B1

This question in 0625/41 May/June 2020

8 (a) A light-emitting diode (LED) is a diode that emits light when there is a current in it. Draw a circuit diagram showing an LED, connected so that it is lit, in series with a battery and a fixed resistor. Use standard electrical symbols. [4] (b) The p.d. across the LED when lit is 3.1 V and the current in the LED is 0.030 A. Calculate the value of the resistance of the LED when lit. resistance = … [2] (c) Fig. 8.1 shows a power supply of e.m.f. 10.5 V connected in series with a lamp and a heater. The p.d. across the lamp is 2.1 V and the current in the lamp is 1.5 A. Fig. 8.1 Calculate: (i) the resistance of the heater resistance = … [2] (ii) the power of the heater. power = … [2] [Total: 10]

10 marks

Mark scheme: 8(a) two circuit symbols correct B1 three circuit symbols correct B1 symbol for cell, battery or power supply AND two other circuit symbols in series B1 LED correct way round B1 8(b) R = V / I in any form OR (R =) V / I C1 (R = 3.1 / 0.030 =) 100 Ω A1 8(c)(i) uses 10.5 = 2.1 + V across heater C1 (R = 8.4 / 1.5 =) 5.6 Ω A1 8(c)(ii) P = VI in any form OR (P =) VI C1 (P = 8.4 × 1.5 =) 12.6 W A1

This question in 0625/42 May/June 2020

9 (a) Complete the truth table shown in Table 9.1 for a NAND gate. Table 9.1 input 1 input 2 output 0 0 0 1 1 0 1 1 [1] (b) The circuit shown in Fig. 9.1 contains two different types of gate, labelled X and Y. A X C B X E Y D Fig. 9.1 Table 9.2 shows a partially completed truth table for this circuit. Table 9.2 input intermediate point output A B C D E 0 0 0 0 0 1 1 0 1 0 1 0 1 1 1 1 (i) From Table 9.2, deduce the name of logic gate Y. Ring your answer from the list. AND NAND NOR NOT OR [1] (ii) Complete the truth table in Table 9.2. [2] (c) There is a current of 3.0 A in a copper wire. Calculate how many electrons pass through the copper wire every 60 s. The charge on an electron is 1.6 × 10–19 C. number of electrons = … [3] [Total: 7]

7 marks

Mark scheme: 9(a) output 1, 1, 1, 0 B1 9(b)(i) AND B1 9(b)(ii) first two lines of E 0,1 B1 last two lines of E 1,1 B1 9(c) Q = It in any form OR (Q =) It C1 (Q = 3 × 60) = 180 (C) C1 (n = 3 × 60 / 1.6 × 10–19) = 1.1 × 1021 C1

This question in 0625/42 May/June 2020

8 (a) (i) Describe what is meant by an electric field. … … [1] (ii) State what is meant by the direction of an electric field. … … [1] (b) Fig. 8.1 shows a polystyrene ball covered with aluminium paint. The polystyrene ball is suspended between two charged metal plates by an insulated thread. insulated thread negatively charged metal plate positively charged metal plate polystyrene ball covered with aluminium paint Fig. 8.1 The ball oscillates between the two charged plates. Explain why the ball oscillates. … … … … … … [4] (c) There is a current of 0.29 A in an electrical circuit. Calculate the time taken for a charge of 15 C to flow through the electrical circuit. time = … [3] [Total: 9]

9 marks

Mark scheme: 8(a)(i) region in which an electric charge experiences a force B1 8(a)(ii) direction of force on a positive charge B1 Question Answer Marks 8(b) any four from: • ball moves towards positive plate • ball touches positive plate • made of conducting material so becomes positively charged • repelled from positive plate • touches negative plate and loses charge • negatively charged ball attracted back to positive plate and process repeats B4 8(c) I = Q / t in any form C1 t = Q / I C1 (t = 15 / 0.29 =) 52 s A1

This question in 0625/43 May/June 2020

8 (a) Explain what is meant by electromotive force (e.m.f.). … … … [2] (b) An electric heater contains two heating elements R1 and R2. An electric motor operates a fan. The fan blows cool air over the heating elements. Fig. 8.1 shows the circuit. S1 S2 S3 240 V mains M supply R1 R2 Fig. 8.1 The heater is powered by a mains supply of e.m.f. 240 V. Switches S1 and S2 are closed. Heating element R1 gets hot. The resistance of R1 is 30 Ω. (i) Calculate the current in heating element R1. current = … [1] (ii) Calculate the power produced in heating element R1. power = … [2] (iii) The resistance of heating element R2 is 60 Ω. Switches S1, S2 and S3 are closed. 1. State and explain how the current in R2 compares with the current in R1. … … … [2] 2. The current in the motor is 0.10 A. The cable from the electric heater to the plug for the mains socket is safe when the current in it is less than 20 A. Suggest and explain a suitable fuse rating for this circuit. … … … … [2] [Total: 9]

9 marks

Mark scheme: 8(a) (related to) energy supplied in driving charge in a circuit / conductor or property of source / battery / cell / power supply B1 energy supplied per / to unit charge or energy transferred to electrical energy or from other form of energy or energy in driving charge around a complete circuit B1 8(b)(i) (I = V ÷ R = 240 ÷ 30 =) 8.0 A B1 8(b)(ii) (P =) VI or 240 × 8.0 C1 1900 W A1 8(b)(iii)1 half (the size) B1 (equal voltage / p.d. / e.m.f. and) resistance is twice the size or I and R are inversely proportional B1 8(b)(iii)2 (fuse rating =) 13 A / 14 A / 15 A / 16 A / 17 A / 18 A / 19 A B1 total current is 12.1 A B1

This question in 0625/41 Oct/Nov 2020

9 (a) Fig. 9.1 shows a circuit. M A Fig. 9.1 On Fig. 9.1, draw two clearly labelled arrows to show the direction of the electron flow and the direction of the conventional current in the circuit. [2] (b) The current in the motor is 13 A. The charge on an electron is 1.6 × 10–19 C. Calculate the number of electrons that pass through the motor every second. number of electrons = … [3] [Total: 5]

5 marks

Mark scheme: 9(a) anti-clockwise arrow labelled (conventional) current somewhere in circuit B1 electron (flow) arrow opposite to (conventional) current B1 9(b) Q = It in any form or (Q =) It OR 13 × 1 C1 (Q = It =) 13 × 1 (= 13 C) C1 (n = 13 / 1.6 × 10–19 =) 8.1 × 1019 A1

This question in 0625/42 May/June 2021

10 (a) Fig. 10.1 shows the potential difference–current graph for a circuit component K. 10.0 8.0 potential difference / V 6.0 4.0 2.0 0 0 1.0 2.0 3.0 4.0 5.0 6.0 current / mA Fig. 10.1 Calculate the resistance of component K when the current in it is 4.0 mA. resistance = … [2] (b) Fig. 10.2 shows a circuit containing component K. component K point X resistor R Fig. 10.2 At low temperature, component K has a much greater resistance than resistor R. At high temperature, component K has a much smaller resistance than resistor R. State and explain the effect on the lamp when the temperature changes from very low to very high. Refer to the voltage at point X in your explanation. statement … explanation … … … … … [4] (c) State the name of component K. … [1] [Total: 7]

7 marks

Mark scheme: 10(a) C1 (R = 9.2 / 0.004 =) 2300 Ω A1 Question Answer Marks 10(b) (much) greater current in lamp OR lamp activated / lights / glows / gets brighter owtte B1 resistance of thermistor / component / K reduced (compared to value at (very) low temperature) B1 voltage / p.d. of point X / across R increases M1 (larger) current in lamp A1 10(c) thermistor B1

This question in 0625/42 May/June 2021

7 (a) Define electromotive force (e.m.f.). … … … [2] (b) Fig. 7.1 shows a circuit. 12 V P Q Fig. 7.1 The two lamps shown are identical. Each lamp has a potential difference (p.d.) of 3.0 V across it and a current of 2.0 A in it. PQ is a length of uniform metal wire. The resistance of PQ is R. (i) Calculate the value of R. R = … [3] (ii) Another piece of wire is made of the same metal as PQ. The length of the new piece of wire is twice the length of PQ. The diameter of the new piece of wire is twice the diameter of PQ. Calculate the resistance of the new piece of wire. resistance = … [3] [Total: 8]

8 marks

Mark scheme: 7(a) energy supplied M1 to drive a unit charge / 1 C round a complete circuit A1 7(b)(i) (R =) 2.3 Ω OR 2.2 Ω A3 R = V/I in any form C1 current in R = 4 (A) OR p.d. across R = 9 (V) C1 7(b)(ii) 1.1 Ω A3 resistance proportional to length (so twice length twice resistance) C1 resistance inversely proportional to area (so twice diameter decreases resistance by factor of 4) C1

This question in 0625/43 May/June 2021

8 A circuit contains two fixed resistors and a light‑dependent resistor (LDR). Fig. 8.1 shows that the power supply is a 9.0 V battery. 9.0 V 450 Ω 800 Ω Fig. 8.1 The current in the 450 Ω resistor is 0.012 A. (a) State what is meant by electric current. … … [1] (b) The current in the LDR is I1 and the current in the 800 Ω resistor is I2. Complete the equation that relates the current in the 450 Ω resistor to I1 and I2. current in the 450 Ω resistor = … [1] (c) Calculate the power dissipated in the 800 Ω resistor. power = … [4] (d) The brightness of the light that is incident on the LDR increases. Explain what happens to the potential difference (p.d.) across the 450 Ω resistor. … … … … [3] [Total: 9]

9 marks

Mark scheme: 8(a) Q / t or (rate of) flow of (electric) charge / electrons B1 8(b) (current in the 450 Ω resistor =) … B1 8(c) (V450 Ω =) IR or 0.012 × 450 or 5.4 (V) or 9.0 – 5.4 or 3.6 (V) seen C1 (I =) 3.6 / 800 or 0.0045 (A) C1 (P =) VI or 3.6 × 0.0045 or 3.62 / 800 C1 1.6 × 10–2 W or 16 mW A1 8(d) resistance (of LDR) decreases B1 current (in circuit) increases or resistance of parallel pair decreases C1 p.d. across 800 Ω resistor increases and p.d. across 450 Ω resistor decreases or resistance of parallel pair a smaller fraction of total resistance and p.d. across 450 Ω resistor decreases A1 I2 – I1

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

8 (a) Fig. 8.1 shows two charged metal plates with a gap between them. The plates are parallel to each other. The top plate is negatively charged and the bottom plate is positively charged. – – – – – + + + + + Fig. 8.1 On Fig. 8.1, draw five electric field lines between the two plates. [2] (b) An electric iron has a power of 2400 W. The potential difference (p.d.) of the mains supply is 220 V. (i) Calculate the electric current in the iron. current = … [2] (ii) Calculate the electric charge which flows through the iron in 15 minutes. charge = … [2] (iii) Fuse ratings of 3 A, 5 A, 10 A, 13 A and 30 A are available. State which of these fuse ratings is suitable for use in the iron. fuse rating … [1] [Total: 7]

7 marks

Mark scheme: 8(a) B2 five straight, parallel vertical lines, equally spaced by eye, between plates B1 arrow head pointing upwards on at least one line and none wrong B1 8(b)(i) 11 A A2 (I =) P / V in any form OR 2400 = I220 C1 8(b)(ii) 9900 C OR 9800 C A2 (Q =) It in any form OR (Q =) 11 × 15 × 60 C1 8(b)(iii) 13 A B1

This question in 0625/43 Oct/Nov 2021

9 Fig. 9.1 shows current–potential difference (p.d.) graphs for a resistor, a thermistor and a filament lamp. 1.0 filamentfilament lamplamp current / A 0.8 resistorresistor 0.6 0.4 thermistorthermistor 0.2 0 0 2 4 6 8 10 12 p.d. / V Fig. 9.1 The resistor, the thermistor and the filament lamp are connected in series with a power supply. (a) (i) Draw a circuit diagram for this circuit. [2] (ii) Add a voltmeter to your circuit diagram in (a)(i) in a correct position to measure the p.d. across the resistor. [1] (iii) Using the graph in Fig. 9.1, determine the p.d. across the terminals of the power supply when the p.d. across the resistor is 6.0 V. p.d. across terminals of power supply = … [4] (b) Describe a practical use for a thermistor. … … [1] [Total: 8]

8 marks

Mark scheme: 9(a)(i) B2 four components joined in series B1 all circuit symbols correct for resistor, thermistor, a filament lamp and a power supply B1 9(a)(ii) voltmeter connected in parallel to the resistor B1 9(a)(iii) (p.d. across terminals of power supply) = 18 V A4 (current through resistor when p.d. across it is 6.0 V =) 0.4 A C1 current same through all components in series circuit OR horizontal line through 0.4 A on graph through all three curves OR p.d. across filament lamp = 3.0 V OR p.d. across thermistor = 9.0 V C1 p.d. across filament lamp = 3.0 V AND p.d, across thermistor = 9.0 V C1 9(b) any sensible use requiring temperature control or depending on temperature, e.g. fire alarms, to keep computers cool (by operating fan), in incubators, electronic thermometer, electronic thermostat in kettle / car engine B1

This question in 0625/43 Oct/Nov 2021

5 Fig. 5.1 shows a kitchen tap that supplies instant boiling water. Fig. 5.1 Cold water passes over an electric immersion heater inside the tap. The boiling point of water is 100 °C. (a) State what is meant by boiling point. … … [2] (b) The immersion heater is powered by the mains at a voltage of 230 V. When the tap is opened, the heater switches on and the current in the heater is 13 A. (i) Calculate the thermal energy produced by the heater in 60 s. thermal energy = … [2] (ii) The specific heat capacity of water is 4200 J / (kg °C). The cold water that enters the tap is at 22 °C. Calculate the rate at which water at its boiling point emerges from the tap. rate = … [4] (c) The metal tap is earthed and there is a fuse in the cable that connects the heater to the mains. 1. Explain how the earth wire protects the user. … … 2. Explain how the fuse protects the circuit. … … [3] [Total: 11]

11 marks

Mark scheme: 5(a) temperature B1 at which liquid becomes a gas or liquid and gas exist together B1 5(b)(i) 1.8  105 J A2 (E =) VIt (in any form) or 230  13  60 or 230  13 or 3000 C1 5(b)(ii) 9.1  10–3 kg / s 9.1  10–3 kg / s A4 (T =) 100 – 22 or 78 or (T =) 100 – 22 or 78 C1 m = E / cT (in any form) or 1.8  105 / (4200  78) or (rate =) P / cT (in any form) or m = E / cT and E = Pt C1 1.8  105 / (4200  78  60) or 5.5  10N or 9.1/9.2  10N or 3000 / (4200  78) or 230  13 / (4200  78) or 9.1 / 9.2  10N C1 5(c) 1 if the tap becomes live or if the (live) cable touches the (metal) tap B1 there is a current to earth / in the earth wire (which blows the fuse) B1 2 the current (in earth wire) is large and fuse melts / blows / stops current / breaks circuit B1

This question in 0625/41 May/June 2022

8 Fig. 8.1 shows how the electromotive force (e.m.f.) of a 60 Hz alternating current (a.c.) power supply varies with time. e.m.f. 0 0 time time period Fig. 8.1 (a) Calculate the time period of the a.c. time period = … [1] (b) Fig. 8.2 shows this power supply connected in a circuit. A B C Fig. 8.2 (i) State the name of component A. … [1] (ii) In each time period of the a.c., 1.5 × 1017 electrons pass through component A. The charge on an electron is 1.6 × 10–19 C. Calculate the average current in the circuit during one time period. current = … [3] (c) On Fig. 8.3: 1. mark, with an arrow labelled E, the direction of the electron flow through component B 2. mark, with an arrow labelled I, the direction of the conventional current in component C. A B C Fig. 8.3 [2] (d) Fig. 8.4 shows a circuit with components B and C connected to a direct current (d.c.) power supply of e.m.f. 12 V. B C Fig. 8.4 The current in the circuit is 0.35 A. Calculate the power delivered by the power supply to the circuit. power = … [2] [Total: 9]

9 marks

Mark scheme: 8(a) 8(b)(i) diode B1 8(b)(ii) (I =) 1.4 A A3 (I =) Q / t in any form C1 (I =) 1.5  1017  1.6  10–19 / 0.017 OR 0.024 / 0.017 C1 Question Answer Marks 8(c) one arrow clockwise AND one arrow anticlockwise B1 arrow anticlockwise (around circuit) labelled I B1 8(d) (P = 0.35  12 =) 4.2 W A2 (P =) IV in any form C1

This question in 0625/42 May/June 2022

7 The electric starter motor in a car is switched on and off using a relay. The relay consists of a plastic case and two flexible springy strips, X and Y, which are made of soft iron. These iron strips act as the switch when a circuit is connected between the terminals W and Z. Fig. 7.1 shows X, Y and the plastic case. W W S springy iron X strips X 12 V car battery Y Y magnetising coil plastic case Z Z Fig. 7.1 Fig. 7.2 Fig. 7.2 shows the equipment from Fig. 7.1 inside a magnetising coil. The magnetising coil is in series with the 12 V car battery and switch S, which is open. (a) Switch S is now closed. Explain what happens to the springy iron strips X and Y. … … … … [3] (b) The power of the starter motor is 1.8 kW and it is also operated by the car battery. (i) Calculate the current in the starter motor when it is used. current = … [2] (ii) The starter motor circuit is connected between terminals W and Z. Explain why copper wires with a large cross-sectional area are used for this circuit. … … … [2] (c) Fig. 7.3 shows the relay and the symbols for the car battery and the starter motor. W S X 12 V car battery Y Z M starter motor Fig. 7.3 The springy iron strips X and Y act as the switch for the starter motor circuit. Complete the circuit diagram for the motor circuit. [2] [Total: 9]

9 marks

Mark scheme: 7(a) B3 X and Y / they become magnetised or they / strips have poles B1 strips in the centre have opposite (magnetic) poles or X and Y attract B1 X and Y touch / close switch / activate relay / complete circuit B1 7(b)(i) 150 A A2 I = P / V in any form or 1.8 / 12 or 1800 / 12 or 1800 / 12 or 0.15 C1 7(b)(ii) B2 small(er) resistance mentioned B1 less thermal energy produced or wires do not melt or large current mentioned B1 7(c) B2 flexible strips in series with motor B1 power supply in series with motor B1 expected answer: W flexible iron S strips X 12 V car battery Y magnetising coil plastic case Z M starter motor

This question in 0625/41 Oct/Nov 2022

8 The unit of the two electrical quantities electromotive force (e.m.f.) and potential difference (p.d.) is the volt (V). (a) State one other similarity between e.m.f. and p.d. … … [1] (b) State one difference between e.m.f. and p.d. … … [1] (c) A battery consists of four cells, each of e.m.f. 1.2 V, in series. (i) Calculate the e.m.f. of the battery. e.m.f. = … [1] (ii) The battery is connected in a circuit with four 12 Ω resistors. Fig. 8.1 is the circuit diagram. V Fig. 8.1 Calculate the total resistance of this arrangement of resistors. resistance = … [3] (iii) Calculate the reading on the voltmeter in Fig. 8.1. reading = … [2] [Total: 8]

8 marks

Mark scheme: 8(a) both relate to energy per unit charge B1 8(b) e.m.f. applies to the whole circuit / source or p.d. to one (or more) component or energy conversion to electrical for e.m.f. or B1 from electrical for p.d. 8(c)(i) 4.8 V B1 8(c)(ii) 20  A3 1 / RT = 1 / R1 + 1 / R2 or (RT =) R1 R2 / (R1 + R2) or 1 / RT = 1 / 24 + 1 / 12 C1 or 1 / RT = 3 / 24 or (RT =) 24 × 12 / (24 + 12) 8.0 () C1 8(c)(iii) 2.9 V A2 V = ER / RT in any form or 4.8  12 / 20 or I = E / R in any form or 0.24 seen C1

This question in 0625/41 Oct/Nov 2022

8 Fig. 8.1 shows apparatus used to charge a metal plate by induction. positively charged plastic rod metal plate lead connected insulator to earth Fig. 8.1 (a) Describe and explain how the apparatus shown in Fig. 8.1 can be used to charge the metal plate. … … … … … … [4] (b) Fig. 8.2 shows an electric circuit. Fig. 8.2 On Fig. 8.2, draw an arrow to show the direction of flow of electrons and explain how you determined the direction. explanation … [1] [Total: 5]

5 marks

Mark scheme: 8(a) positively charged / plastic rod is brought close to metal plate B1 negative charges / electrons (from metal plate) move to top of metal plate / close(r) to rod B1 earth lead connected to (metal) plate AND negative charges / electrons move on to plate B1 (at the end of the process) earth lead removed (before charged rod removed) B1 OR (at the end of the process) metal plate has (net) negative charge 8(b) correct direction – pointing away from negative terminal / clockwise arrow B1 AND current flow in opposite direction to flow of electrons

This question in 0625/43 Oct/Nov 2022

6 (a) Sound waves have compressions and rarefactions. Explain what is meant by compression and rarefaction. compression … … rarefaction … … [2] (b) We can see light from the Sun but we cannot hear any sound from it. State the reason for this. … … [1] (c) During a thunderstorm, an observer sees the lightning almost immediately but hears the sound of the thunder several seconds later. The thunder and lightning are produced at the same time. The sound of the thunder is heard 9.0 s after the lightning is seen. The speed of sound in air is 340 m / s. Calculate the distance from the thunderstorm to the observer. distance = … [2] (d) In a lightning strike, there is a current of 3.0 × 104 A for 48 ms. Calculate the charge that flows. charge = … [3] [Total: 8]

8 marks

Mark scheme: 6(a) (region where) particles are close(r) together (than normal) OR (region where) there is a great(er) pressure (than normal) B1 (region where) particles are further / far apart (than normal) OR (region where) there is a low(er) pressure (than normal) B1 6(b) light does not need a medium to travel through OR sound needs a medium to travel through (and there is no medium B1 between Sun and Earth) 6(c) 3100 m OR 3.1 km A2 v = s / t OR (s =) vt OR 340  9 (C1) 6(d) 1400 C A3 I = Q / t OR (Q = )I t OR 3.0  104  48  10–3 (C1) (t =) 48  10–3 OR (t =) 4.8  10–2 OR (t =) 0.048 SEEN (C1)

This question in 0625/42 Feb/March 2023

7 (a) Define potential difference (p.d.). … … [2] (b) (i) State the equation which defines electromotive force (e.m.f.) E. [1] (ii) The e.m.f. of a battery is 9.0 V. The battery is in a circuit. Calculate the work done by the battery when it moves a charge of 30 C around a complete circuit. work done = … [2] (c) A circuit consists of a d.c. power supply, a lamp and a thermistor. (i) Draw a circuit diagram of these components connected in series. [2] (ii) Explain what happens in the circuit you have drawn in (c)(i) when the temperature of the thermistor is increased. … … … [2] [Total: 9]

9 marks

Mark scheme: 7(a) work done in passing charge through / across a component B1 work done per unit charge B1 7(b)(i) (definition of emf:) E = W / Q B1 7(b)(ii) 270 J A2 W = EQ OR 9.0  30 (C1) 7(c)(i) correct symbols for d.c. power supply, a lamp and a thermistor B1 three components in a complete series circuit B1 7(c)(ii) resistance (of thermistor) decreases (when temperature increases) B1 resistance of circuit decreases OR greater current (in lamp so brightness of lamp increases) OR greater p.d. across lamp B1 (so brightness of lamp increases)

This question in 0625/42 Feb/March 2023

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

7 (a) A plastic rod is uncharged. When the rod is rubbed with a woollen cloth, the rod becomes negatively charged. Explain, in terms of particles, why the rod becomes negatively charged. … … … [2] (b) Fig. 7.1 shows a negatively charged metal sphere S. – – – – – sphere S Fig. 7.1 There is an electric field surrounding S. (i) State what is meant by an electric field. … … [1] (ii) On Fig. 7.1, draw the pattern of the electric field surrounding sphere S and indicate its direction. [2] (c) Fig. 7.2 shows a small negative charge Z placed near to sphere S. – – – – – Z sphere S Fig. 7.2 Charge Z experiences a force due to the electric field surrounding S. On Fig. 7.2, draw an arrow to show the direction of this force on Z. [1] [Total: 6]

6 marks

Mark scheme: 7(a) electrons move from cloth to rod A2 (plastic) rod gains electrons C1 7(b)(i) (region) where an (electric) charge experiences a force B1 7(b)(ii) At least three radial field lines distributed evenly around outside of S AND touching S AND not inside S B1 arrow on (at least one) field line pointing towards S B1 7(c) arrow through Z and away from (centre of) sphere B1

This question in 0625/41 Oct/Nov 2023

8 A cylinder is made of modelling clay. The modelling clay is an electrical conductor. Fig. 8.1 shows the cylinder. cross-sectional area length Fig. 8.1 The cylinder is connected into a circuit. Fig. 8.2 shows that the circuit also includes a battery of electromotive force (e.m.f.) 9.0 V and a resistor P. 9.0 V P cylinder of modelling clay Fig. 8.2 The resistance of P is 4.0 Ω. The current in P is 1.5 A. (a) Calculate: (i) the magnitude X of the charge that flows through P in 600 s X = … [2] (ii) the resistance of the cylinder of modelling clay. resistance = … [3] (b) The cylinder is removed from the circuit and replaced with a new cylinder made of the same modelling clay. The new cylinder is twice the length and has half the cross-sectional area of the first cylinder. Calculate the time that it now takes for a charge of magnitude X to flow through resistor P. time = … [4] [Total: 9]

9 marks

Mark scheme: 8(a)(i) 900 C A2 I = Q / t OR (Q =) It OR 1.5  600 C1 8(a)(ii) 2.0  A3 R = V / I OR (Rtot =) V / I OR 9.(0) / 1.5 or 6.(0) C1 (Rcyl =) total resistance – P OR (Rcyl =) 6.0 – 4.0 C1 8(b) 1200 s A4 R is directly proportional to l OR (new cylinder) twice as long means twice R C1 R is inversely proportional to A OR (new cylinder) half cross-sectional area means twice R C1 (resistance of cylinder =) 4  (a)(ii) () C1

This question in 0625/41 Oct/Nov 2023

6 Fig. 6.1 shows the circuit diagram for a flashlight (torch). Fig. 6.1 The electromotive force (e.m.f.) of the battery is 4.5 V. The circuit contains a 60 Ω fixed resistor. The current in the light-emitting diode (LED) is 0.020 A. (a) Calculate the potential difference (p.d.) across the LED. p.d. = … [2] (b) Explain why the LED does not light up if the battery is reversed. … … [1] (c) The chemical energy stored in the battery is 1050 J. Show that the flashlight operates for approximately 3 h. [2] (d) Calculate the total charge that flows through the LED in 3600 s. charge = … [2] [Total: 7]

7 marks

Mark scheme: 6(a) (p.d. across LED = 4.5 – 1.2 =) 3.3 V A2 (V =) IR C1 6(b) LED (is a diode, which) only allows current in one direction / has a very high resistance (when direction of current is B1 reversed.) OR (it) is reverse-biased 6(c) E=IVt OR (t =) E / VI OR Q = E / V AND Q = I  t B1 (t =) 1050  [0.02  4.5  3600] OR (t =) 3.2 h B1 6(d) (charge =) 72 C A2 I =Q / t OR (Q =) It OR (Q =) 0.02(0)  3600 C1

This question in 0625/42 Oct/Nov 2023

6 Fig. 6.1 shows an isolated metal sphere suspended by an insulating thread from the ceiling. insulating thread metal sphere Fig. 6.1 The sphere is negatively charged. (a) The charge on the sphere produces an electric field in the surroundings. (i) State what is meant by ‘electric field’. … … [1] (ii) Draw on Fig. 6.1 to show the pattern and direction of the electric field produced by the charge on the sphere. Draw at least four lines. [3] (b) The magnitude of the charge on the sphere is 3.5 × 10–10 C. An earthed metal wire is touched against the surface of the sphere and the sphere is discharged. (i) State what happens in the wire as the sphere is discharged. … … … [2] (ii) It takes a time of 0.14 ns for the sphere to discharge completely. Calculate the average current in the earthed wire as the sphere discharges. average current = … [3] [Total: 9]

9 marks

Mark scheme: 6(a)(i) (region) where (an electric) charge experiences a force OR (region) where a force acts on a (an electric) charge B1 6(a)(ii) at least four straight radial lines AND evenly spaced (by eye) surrounding sphere B1 four lines touching sphere AND no lines inside sphere B1 at least one arrowhead towards sphere AND no incorrect arrowheads B1 Question Answer Marks 6(b)(i) electrons move (through the wire) from the sphere OR electrons move (through the wire) to(wards) the Earth A2 electrons move (in the wire) C1 6(b)(ii) 2.5 A A3 I = Q / t OR (I =) Q / t OR 3.5  10–10 / 1.4  10–10 C1 2.5  10N C1

This question in 0625/41 May/June 2024

7 The electromotive force (e.m.f.) of a battery is 7.5 V. (a) Define the term electromotive force. … … … [2] (b) The battery is connected in series with a variable resistor and a 30 Ω resistor. The battery is made using 1.5 V cells. (i) Draw a circuit diagram that shows all the 1.5 V cells connected to produce an e.m.f. of 7.5 V, the variable resistor and the 30 Ω resistor. [3] (ii) The resistance of the variable resistor can be varied from 0 Ω to a maximum resistance of 150 Ω. Using the axes in Fig. 7.1, draw a graph to show how the current in the circuit varies with the resistance of the variable resistor as it increases from 0 Ω to 150 Ω. Determine and label the value of the maximum current on the y-axis. current / A 0 0 75 150 resistance of variable resistor / Ω Fig. 7.1 [4] [Total: 9]

9 marks

Mark scheme: 7(a) (electrical) work done moving a unit charge around a (complete) circuit A2 work done AND moving a charge (in a circuit) C1 7(b)(i) correct symbols for five cells in series B1 correct symbols for variable resistor AND fixed resistor B1 cells, variable resistor and fixed resistor connected in series B1 7(b)(ii) curve with negative gradient of decreasing magnitude from 0  to 150 AND does not reach the x-axis A2 curve / line with negative gradient from 0  to 150  C1 y-axis labelled 0.25 where candidate’s line meets the y-axis OR the mark on the y-axis labelled 0.25 A2 R = V / I OR (Imax =) V / R OR 7.5 / 30 C1

This question in 0625/41 May/June 2024

7 Fig. 7.1 shows two charged metal plates. X marks the position of the centre of the space between the plates. positively charged + + + + + + + + + plate X – – – – – – – – – negatively charged plate Fig. 7.1 (a) (i) On Fig. 7.1, draw at least four field lines to show the pattern and the direction of the electric field between the two charged plates. [2] (ii) Describe the effect on a negatively charged particle placed at X. … … [1] (b) During a thunderstorm, an electric field is set up between a cloud and the ground. Charges on the cloud and on the ground are shown in Fig. 7.2. cloud _ _ _ _ _ path of lightning ground + + + + + + Fig. 7.2 The lightning shown in Fig. 7.2 discharges a current of 28 000 A for 0.0012 s. (i) Calculate the charge that flows from the cloud to the ground. charge = … [2] (ii) The lightning transfers 1.2 × 108 J of energy. Calculate the potential difference between the base of the cloud and the ground. potential difference = … [2] [Total: 7]

7 marks

Mark scheme: 7(a)(i) evenly spaced straight vertical lines from one plate to the other B1 arrows on lines pointing towards negatively charged plate B1 7(a)(ii) (negatively charged particle has) force / attraction towards positively charged / positive (plate) B1 7(b)(i) 34 C A2 I = Q / t OR (Q =) It OR 28 000  0.0012 C1 7(b)(ii) (p.d. =) 3.6 MV OR 3.6  106 V A2 E = ItV OR (V =) E / It OR (V =) E / Q OR (V =) 1.2  108 / 34 C1

This question in 0625/43 May/June 2024

6 A potential divider is made by connecting a light-dependent resistor (LDR) and a thermistor in series. Fig. 6.1 shows the potential divider, a voltmeter and a direct current (d.c.) power supply connected into a circuit. + – V Fig. 6.1 The voltmeter measures the potential difference (p.d.) across the LDR. (a) Define potential difference (p.d.). … … … [2] (b) The electromotive force (e.m.f.) of the supply is E. Describe how the p.d. across the thermistor can be determined using the reading on the voltmeter. … … [1] (c) The resistance of the LDR decreases and the resistance of the thermistor increases. (i) State what has happened to the light intensity incident on the LDR and the temperature of the thermistor. intensity of incident light on LDR: … temperature of thermistor: … [1] (ii) Explain what happens to the reading on the voltmeter. … … … … [3] [Total: 7]

7 marks

Mark scheme: 6(a) work done by a unit charge passing through a component A2 (electrical) work done AND moving charge C1 6(b) (p.d. =) E – reading on voltmeter OR subtract reading on voltmeter from E B1 6(c)(i) (intensity of light on LDR) increased B1 AND (temperature of thermistor) decreased 6(c)(ii) reading on voltmeter / it decreases B1 Any two from: B2 1 e.m.f. is constant 2 RLDR / Rthermistor decreases OR RLDR is a smaller proportion of the total resistance 3 VLDR / Vthermistor decreases OR VLDR is a smaller proportion of e.m.f. R 1 V 1 4 = R 2 V 2

This question in 0625/41 Oct/Nov 2024

5 Fig. 5.1 shows a metal sphere S. The sphere has been charged with a negative charge. S Fig. 5.1 (a) (i) There is an electric field around sphere S. On Fig. 5.1, draw four field lines to show the pattern of the field and indicate the direction of the field with arrows on the lines. [2] (ii) Fig. 5.2 shows a position X next to sphere S. A small negatively charged particle is placed at position X. X S Fig. 5.2 State the direction of the force on the negatively charged particle at X due to the electric field around sphere S. … [1] (iii) The negatively charged particle at X is released from rest. Describe the motion of the small negatively charged particle due to the electric field around sphere S. … … … [2] (b) Fig. 5.3 shows sphere S being spray painted. Sphere S is negatively charged. As the paint particles exit the wide nozzle of the paint sprayer, they become charged with a positive charge. paint particles paint sprayer S positively charged nozzle Fig. 5.3 (i) Explain why the paint particles spread out when they leave the nozzle. … … [1] (ii) The sphere can be painted by hand using a paintbrush. Suggest and explain one advantage to using charged paint from a spray gun to paint sphere S. advantage … explanation … … … [2] [Total: 8]

8 marks

Mark scheme: 5(a)(i) four evenly spaced radial lines touching S AND no lines inside S B1 at least one arrow pointing towards S and none incorrect B1 5 (a)(ii) to the left OR away from the sphere / S B1 5(a)(iii) accelerates (due to a resultant force) B1 (moves) away from the (centre of the) sphere B1 5(b)(i) like charges repel B1 5(b)(ii) advantage: more even coat or less chance of paint particles clumping together or less chance of creating thicker patches B1 explain: positive / paint particles are attracted (by the same amount) to all parts of the negative sphere so they spread out B1 or paint creates a fine mist so spreads out (over the surface) OR advantage: more durable or better adhesion or cheaper or high transfer efficiency or less paint wasted or fewer drips or (B1) less paint sag or less overspray on floor / walls explain: the positive/paint is attracted to the negative sphere / charges and forms a strong(er) bond (B1) OR advantage: quicker to paint (B1) explain: all surface is painted at the same time without having to turn the sphere / go around the other side owtte (B1)

This question in 0625/43 Oct/Nov 2024

5 A light-dependent resistor (LDR) has a low resistance in high light intensity and a high resistance in the dark. (a) Sketch a graph of resistance (y-axis) against light intensity (x-axis) for an LDR. [2] (b) Fig. 5.1 shows part of the electric circuit used to turn on a light when it is dark. fixed resistor Fig. 5.1 (i) Complete the circuit in Fig. 5.1 with the symbol for a light-dependent resistor (LDR). [1] (ii) Explain why the lamp is off in the light and the lamp is on in the dark. Use ideas about potential difference (p.d.) in your answer. … … … … [3] [Total: 6]

6 marks

Mark scheme: 5(a) y-axis labelled resistance AND x-axis labelled light intensity B1 Straight line / smooth curve with negative gradient B1 5(b)(i) B1 Correct symbol drawn to complete circuit. 5(b)(ii) in the dark, VLDR is a bigger proportion of e.m.f OR A2 when RLDR is high VLDR is a bigger proportion of e.m.f. OR when VLDR is high VLDR is a bigger proportion of e.m.f. In the dark, VLDR is high OR C1 when RLDR high, VLDR is high Any one from: B1 • emf shared (between fixed resistor and LDR) OR emf is constant • VLDR = VLAMP OR p.d. is the same across components in parallel

This question in 0625/42 Feb/March 2025

7 (a) State what is meant by an electric field. … … [1] (b) A plastic rod is rubbed with a cloth. The plastic rod becomes negatively charged and the cloth becomes positively charged. (i) Explain why. … … … [2] (ii) The negatively charged plastic rod is suspended by an insulating thread. Another negatively charged plastic rod is brought close to the suspended rod. State what happens to the suspended plastic rod. … [2] (c) (i) Define the kilowatt-hour (kW h) in words. … … [1] (ii) A small lamp illuminates an electric oven. The lamp has an output power of 25 W and operates for 220 hours in one year. The p.d. across the lamp is 230 V. 1. Calculate the energy transferred by the lamp in one year. Give your answer in kW h. energy = … kW h [2] 2. Calculate the current in the lamp. current = … [2] [Total: 10]

10 marks

Mark scheme: 7(a) (region) where a(n electric) charge experiences a force B1 OR (region) where a force acts on a(n electric) charge 7(b)(i) any two from: B2 • friction (between cloth and rod causes electrons to gain energy) • electrons move • (electrons move) from cloth / to plastic (making plastic negative and cloth positive) 7(b)(ii) moves away (from the charged plastic rod) A2 moves / experiences a force / repels C1 7(c)(i) energy transferred in one hour at a rate of transfer of 1 kW B1 7(c)(ii) 1 5.5 (kW h) A2 P = (∆)E ÷ t OR (∆E =) Pt OR (∆E =) 0.025  220 OR 25  220 C1 2 0.11  A A2 P = V I OR (I =) P ÷ V OR (I =) 25 ÷ 230 C1

This question in 0625/42 May/June 2025

8 (a) (i) State what is meant by an electric field. … … [1] (ii) Fig. 8.1 shows a negative point charge. negative point charge − Fig. 8.1 On Fig. 8.1, draw four field lines to show the pattern and the direction of the electric field due to the negative point charge. [2] (b) The potential difference (p.d.) of a lightning strike is 2.9 × 108 V. The energy transferred by the lightning strike is 4.5 × 105 MJ. Calculate the charge that flows. charge = … [3] (c) The current in a lamp is 2.0 A. The lamp is switched on for a time of 120 s. Calculate the charge that flows. charge = … [2] [Total: 8]

8 marks

Mark scheme: 8(a)(i) (region) where (an electric) charge experiences a force B1 OR (region) where a force acts on a (an electric) charge 8(a)(ii) four radial straight field lines starting at charge B1 at least one arrow on a field line towards the charge B1 8(b) 1600 C A3 V = W / Q OR (Q =) W / V C1 (Q =) 4.5  10N ÷ 2.9  108 OR 1.6  10N C1 8(c) 240 C A2 (Q =) It OR 2(.0)  120 C1

This question in 0625/43 May/June 2025

9 (a) Fig. 9.1 shows a transformer. soft-iron core primary secondary coil coil Fig. 9.1 (i) There is an alternating current in the primary coil. Describe how an alternating current is produced in the secondary coil. … … … … [3] (ii) A step-up transformer has a turns ratio of 1 : 20. The voltage across the primary coil is 12 V. Calculate the voltage across the secondary coil. voltage across secondary coil = … [2] (b) The power lost in a cable is 1.25 × 10–3 W. The resistance of the cable is 0.050 Ω. Calculate the current in the cable. current = … [2] (c) State two advantages of high-voltage transmission. 1 … … 2 … … [2] [Total: 9]

9 marks

Mark scheme: 9(a)(i) any three from: B3 • (current in the primary coil generates a) changing magnetic field (in primary coil) • (iron) core transfers the magnetic field (to the secondary coil) • secondary coil cuts the magnetic field / secondary coil is in (changing) magnetic field • an e.m.f. is induced (in the secondary coil) • (induced) current changes direction because the magnetic field changes direction 9(a)(ii) 240 V A2 Vs ÷ Vp = Ns ÷ Np OR (Vs =) 12  20( ÷ 1) C1 9(b) 0.16 A A2 P = I2R OR I2 = P ÷ R OR I2 = 1.25  10–3 ÷ 0.05(0) OR I2 = 0.025 C1 9(c) any two from: B2 • less power / heating / energy losses • thinner / cheaper cables • pylons further apart / fewer pylons • transfer energy over long(er) distance

This question in 0625/43 May/June 2025

3 Fig. 3.1 shows black solar panels installed on the roof of a house and a large rechargeable battery. solar panels electric cable large rechargeable battery Fig. 3.1 (not to scale) The solar panels produce electricity and give a maximum power output of 3.5 kW. The efficiency of the solar panels is 16%. (a) State and explain one advantage of using black solar panels. … … … [2] (b) Calculate the power received by the solar panels from the Sun. power = … [3] (c) The solar panels produce direct current (d.c.) and household appliances use alternating current (a.c.). State the difference between alternating current and direct current. … … [1] (d) Suggest one advantage of storing energy in the large rechargeable battery. … … [1] (e) Calculate the charge that flows into the battery when there is a current of 4.0 A for 2.0 hours. charge = … [3] [Total: 10]

10 marks

Mark scheme: 3(a) more electricity generated OR makes solar panels more efficient B1 black is a good absorber OR black is a poor reflector owtte B1 3(b) 22 kW OR 22 000 W A3 (total power input =) {useful power output ( 100%)} / (%) efficiency C1 OR (total power input =) {3.5  100} / 16 OR (total power input =) 3.5 / 0.16 (total power input =) 3.5 / 0.16 OR (total power input =) {3.5  100} / 16 C1 3(c) alternating current reverses direction OR direct current is only in one direction B1 3(d) electricity can be used when there is no Sun OR when it is dark or cloudy OR at night B1 3(e) 29 000 C A3 (Q =) I t OR (Q =) 4.0  2.0  60  60 C1 correct conversion from h to s SEEN C1

This question in 0625/42 Oct/Nov 2025

7 A circuit consists of an a.c. supply and two lamps. The lamps are connected in parallel. (a) Draw the circuit diagram. [2] (b) The electromotive force (e.m.f.) of the a.c. supply is 230 V. When connected to the 230 V supply, the resistance of one lamp is 1200 Ω and the resistance of the other lamp is 800 Ω. (i) Calculate the current in the 800 Ω lamp. current = … [2] (ii) Calculate the energy used by the 800 Ω lamp in 5.0 hours. Give your answer in kWh. energy = … kWh [3] (iii) Calculate the combined resistance of the two lamps in this circuit. resistance = … [2] [Total: 9]

9 marks

Mark scheme: 7(a) correct symbols for a.c supply and lamps B1 components all connected in parallel B1 7(b)(i) 0.29 A A2 (I =)V / R OR (I =)230 / 800 C1 7(b)(ii) 0.33 (kWh) A3 (E =)VIt OR (E =) {230  0.29  5(.0)} / 1000 C1 conversion from W to kW seen i.e. division by 1000 C1 7(b)(iii) 480  A2 1 / R = 1 / R1 + 1 / R2 OR 1 / R = 1 / 800 + 1 / 1200 OR (R =) R1R2 / {R1 + R2} OR C1 (R =) {800  1200} / {800 + 1200}

This question in 0625/42 Oct/Nov 2025