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0625/42/F/M/16© UCLES 2016

8 (a) Fig. 8.1 shows 3 lamps and a fuse connected to a power supply.

220 V

Fig. 8.1

The e.m.f. of the supply is 220 V. Each lamp is labelled 220 V, 40 W. The rating of the fuse is 2.0 A.

Calculate

(i) the current in each lamp,

current = ...........................................................[2]

(ii) the current in the fuse,

current = ...........................................................[1]

(iii) the total number of lamps, all in parallel, that could be connected without blowing the fuse.

number = ...........................................................[2]

CURRENT OF ELECTRICITY IGCSE PHYSICS - Page: 1 - MR.AFZAL AMIN

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0625/42/F/M/16© UCLES 2016 [Turn over

(b) After a very long period of use, the wire filament of one of the lamps becomes thinner.

(i) Underline the effect of this change on the resistance of the filament.

resistance increases resistance remains the same resistance decreases [1]

(ii) State and explain the effect of this change on the power of the lamp.

...........................................................................................................................................

...........................................................................................................................................

.......................................................................................................................................[2]

[Total: 8]


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Fig. 9.1 shows a 12V battery connected in a circuit containing resistors A, B, C and D. Each resistorhas a resistance of 6.0Ω.

9

A B

C

D

12 V

Fig. 9.1

Calculate the combined resistance of(a)

resistors A and B,(i)

resistance = ................................................................. [1]

resistors A, B and C,(ii)

resistance = ................................................................. [2]

resistors A, B, C and D.(iii)

resistance = ................................................................. [1]

06_0625_41_2016_1.10© UCLES 2016CURRENT OF ELECTRICITY IGCSE PHYSICS - Page: 3 - MR.AFZAL AMIN

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Calculate(b)

the current in the battery,(i)

current = ................................................................. [1]

the energy transferred from the battery to the circuit in 50s.(ii)

energy transferred = ................................................................. [2]

[Total: 7]

[Turn over06_0625_41_2016_1.10© UCLES 2016CURRENT OF ELECTRICITY IGCSE PHYSICS - Page: 4 - MR.AFZAL AMIN

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Fig. 10.1 shows part of the circuit of a hair-dryer with a 240V a.c. supply.10

ZY

XA

BC

240 V

Fig. 10.1

The switch can be in one of three positions:

• position A: off (as shown),• position B: low heater power,• position C: high heater power.

All three heaters X, Y and Z each have a power of 1000W when used in this hair-dryer.

Heaters Y and Z have equal resistances.

Calculate

the resistance of heater X,(a)

resistance = ................................................................. [2]

the resistance of heater Y,(b)

resistance = ................................................................. [1]


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the current in heater Z when the switch is in position C.(c)

current = ................................................................. [2]

[Total: 5]


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A lightning conductor protects a tall building and the people in it against damage and injury causedby lightning strikes.

7

The lightning conductor is a very long strip of copper that is attached to the side of the building. Atthe top of the building, the strip of copper is connected to a vertical metal pole and at the bottomof the building, it is buried in the ground.

Fig. 7.1 shows a thundercloud passing over the building.

building

ground

metal pole

lightning

conductor

– – – – – –

thundercloud

Fig. 7.1

The bottom of the thundercloud is negatively charged.

As the cloud moves closer to the building, the top of the metal pole becomes charged.

State the sign of the charge at the top of the metal pole. Explain, in terms of the particlesinvolved, how it becomes charged.

(a)

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

........................................................................................................................................... [2]


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As the cloud passes over the building, a lightning strike occurs and a charge of 0.84C flowsthrough the lightning conductor. The charge flows for 3.5 × 10–5 s.

(b)

Calculate the average current in the lightning conductor during this time.(i)

current = ................................................................. [2]

It is suggested that the current in the lightning conductor could be measured byconnecting a laboratory ammeter between the pole and the copper strip.

State one reason why this cannot be successful.

(ii)

................................................................................................................................

................................................................................................................................ [1]

The copper strip has a large cross-sectional area.

State how increasing the cross-sectional area of the copper strip affects its resistance.

(c)

...........................................................................................................................................

........................................................................................................................................... [1]

[Total: 6]


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0625/41/O/N/16© UCLES 2016 [Turn over

9 Fig. 9.1 shows a gardener cutting damp grass with a high-powered electric mower.

weather-proofsocket on wall damp grass

gardener

electricmower

cut in insulationcovered with tape

socket designedfor indoor use

excess length ofcable coiled up

extension cablewith thin wires

plug

Fig. 9.1

The mower cable has thick wires appropriate for the current of the mower and the correct fuse. This cable is too short, and so the gardener uses an extension cable with thin wires, intended for use with a reading lamp. This cable has no fuse.

Discuss any dangers of the electrical arrangement shown in Fig. 9.1.

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

......................................................................................................................................................[4]

[Total: 4]


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0625/42/O/N/16© UCLES 2016

9 Fig. 9.1 is a circuit diagram.

55

60

30

Fig. 9.1

The circuit consists of three resistors and three identical 1.5 V cells.

(a) State the total electromotive force (e.m.f.) of the three 1.5 V cells in series.

total e.m.f. = .......................................................... [1]

(b) Calculate

(i) the combined resistance of the resistors in parallel,

resistance = .......................................................... [2]

(ii) the total resistance of the circuit,

resistance = .......................................................... [1]

(iii) the current in the 55 Ω resistor.

current = .......................................................... [2]


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(c) The currents in the 30 Ω, the 55 Ω and the 60 Ω resistors are all dif ferent.

State the resistance of the resistor in which the current is

(i) the largest,

resistance = .......................................................... [1]

(ii) the smallest.

resistance = .......................................................... [1]

[Total: 8]


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0625/43/O/N/16© UCLES 2016

9 A circuit consists of a 12 V battery, three resistors and a switch.

Fig. 9.1 is the circuit diagram.

12 V

20 Ω

24 Ω

28 Ω

Fig. 9.1

(a) The battery consists of 2.0 V cells in series.

State the number of 2.0 V cells in series in the battery.

number of cells = .......................................................... [1]

(b) Calculate

(i) the combined resistance of the two resistors in series,

resistance = .......................................................... [1]

(ii) the total resistance of the circuit.

resistance = .......................................................... [2]


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(c) The switch is closed.

Calculate

(i) the current in the 20 Ω resistor,

current = .......................................................... [2]

(ii) the charge that flows through the 20 Ω resistor in 6.0 minutes.

charge = .......................................................... [2]

[Total: 8]


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0625/42/F/M/17© UCLES 2017

9 Fig. 9.1 shows a graph of current against potential difference (p.d.) for a filament lamp.

00

0.20

0.40

0.60

0.80

current / A

2.0 4.0 6.0p.d. / V

8.0

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]


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0625/42/F/M/17© UCLES 2017 [Turn over

(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]


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0625/42/F/M/17© UCLES 2017

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]


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0625/41/M/J/17© UCLES 2017 [Turn over

9 (a) The resistance of a circuit component varies with the brightness of the light falling on its surface.

(i) State the name of the component.

.......................................................................................................................................[1]

(ii) Draw the circuit symbol for this component.

[1]

(b) Fig. 9.1 shows a 6.0 V battery connected in series with a 1.2 kΩ resistor and a thermistor.

1.2 kΩ

6.0 V

V

Fig. 9.1

(i) At a certain temperature, the resistance of the thermistor is 2.4 kΩ.

Calculate the reading on the voltmeter.

voltmeter reading = ...........................................................[4]

(ii) The battery connected to the circuit in Fig. 9.1 is not changed.

Suggest a change that would cause the reading of the voltmeter to decrease.

.......................................................................................................................................[1][Total: 7]


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0625/42/M/J/17© UCLES 2017

8 Fig. 8.1 shows a 12.0 V power supply connected in a circuit.

12.0 V

A X B

slidingcontact

resistancewire

Fig. 8.1 (not to scale)

The circuit includes a lamp and a resistance wire AB of constant cross-sectional area. There is a sliding contact that can be moved between A and B.

(a) The rating of the lamp at normal brightness is 6.0 V, 9.0 W. Calculate (i) the current in the lamp at normal brightness,

current = ...........................................................[2]

(ii) the resistance of the lamp at normal brightness.

resistance = ...........................................................[2]


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(b) AB is 1.00 m long and has a resistance of 5.0 Ω. The lamp has normal brightness when the sliding contact is at X.

(i) The sliding contact is moved to B.

Explain, without a calculation, why the lamp becomes dimmer.

...........................................................................................................................................

...........................................................................................................................................

.......................................................................................................................................[1]

(ii) Calculate the distance AX for the lamp to have normal brightness.

distance AX = ...........................................................[3]

[Total: 8]


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0625/43/M/J/17© UCLES 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.

X

YA B

12 V

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]


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(c) Resistor X is removed from the circuit in Fig 9.1.

Explain why the lamp becomes dimmer.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...............................................................................................................................................[2]

[Total: 9]


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9 Fig. 9.1 shows a circuit with three 1.5 V cells.

3.0 Ω

6.0 Ω

A

C D

E

B G

F

H

Fig. 9.1

(a) Calculate

(i) the total electromotive force (e.m.f.) of the cells,

e.m.f. = ...........................................................[1]

(ii) the total resistance of the circuit,

resistance = ...........................................................[3]

(iii) the current in the 3.0 Ω resistor.

current = ...........................................................[2]

(b) State, using the letters in Fig. 9.1, how you would connect

(i) an ammeter to measure the total current in the circuit,

...........................................................................................................................................

.......................................................................................................................................[1]

(ii) a voltmeter to measure the potential difference (p.d.) across the 6.0 Ω resistor.

...........................................................................................................................................

.......................................................................................................................................[1]

[Total: 8]CURRENT OF ELECTRICITY IGCSE PHYSICS - Page: 22 - MR.AFZAL AMIN

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8 Fig. 8.1 is a circuit diagram.

24 V

8.0 Ω 4.0 Ω

6.0 Ω

Fig. 8.1

Calculate

(a) the resistance of the circuit,

resistance = ...........................................................[4]

(b) the potential difference (p.d.) across the 8.0 Ω resistor.

p.d. = ...........................................................[2]

[Total: 6]


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0625/41/M/J/18© UCLES 2018

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.

A second cylindrical wire W2 having length l2 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]


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0625/42/M/J/18© UCLES 2018

8 Fig. 8.1 shows a circuit that contains a battery of electromotive force (e.m.f.) 6.0 V, an ammeter, a 20 Ω resistor and component X.

A

20 Ω

6.0 V

X

Fig. 8.1

(a) (i) State the name of component X.

.......................................................................................................................................[1]

(ii) The potential difference (p.d.) across the 20 Ω resistor is measured with a voltmeter.

On Fig. 8.1, draw the symbol for this voltmeter connected to the circuit. [1]

(b) The p.d. across the 20 Ω resistor is varied from zero to 6.0 V. For each value of p.d. a corresponding current is measured.


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On Fig. 8.2, draw a line to indicate how the current measured by the ammeter depends on the p.d. across the 20 Ω resistor.

00

0.10

0.20

0.30

0.40

1.0 2.0p.d. / V

current / A

3.0 4.0 5.0 6.0

Fig. 8.2 [3]

(c) A second resistor is connected into the circuit in parallel with the 20 Ω resistor.

(i) State how the combined resistance of the two resistors in parallel compares with the resistance of each of the resistors on its own.

...........................................................................................................................................

.......................................................................................................................................[1]

(ii) The p.d. across the two parallel resistors is changed and the current in the battery for each value of the p.d. is measured. A second line could be drawn on Fig. 8.2 to indicate how the current measured by the ammeter depends on the p.d. across the two resistors in parallel.

State how the second line differs from the original line. You are not expected to draw this second line.

...........................................................................................................................................

.......................................................................................................................................[1]

[Total: 7]


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9 Fig. 9.1 shows a circuit that includes a battery of electromotive force (e.m.f.) 12 V.

A V

20 Ω

12 V

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]


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