CAIE IGCSE Physics 4.2.4 Resistance Topic Practice

Question 1

[Maximum number: 3]

Fig. 8.2 shows another circuit. Lamps A and B are identical filament lamps.

Fig. 8.2

Fig. 8.2

The current supplied by the power supply is 0.50 A .
Calculate the resistance of lamp A.
resistance =

Question 2

[Maximum number: 1]

A student determines the resistance of resistor R. She uses a circuit including a voltmeter and an

ammeter.

Which circuit does she use?

A
Figure for Question 2 — CAIE IGCSE Physics — Option A
B
Figure for Question 2 — CAIE IGCSE Physics — Option B
C
Figure for Question 2 — CAIE IGCSE Physics — Option C
D
Figure for Question 2 — CAIE IGCSE Physics — Option D

Question 3

[Maximum number: 2]

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 \(\mathrm{X

Fig. 7.1 shows \(\mathrm{X

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.

The power of the starter motor is 1.8 kW and it is also operated by the car battery.

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.

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