CAIE IGCSE Physics 4.2.4 Resistance Topic Practice

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Covered syllabus points

4.2.4.1—Resistance: R = V/I4.2.4.2—An experiment to determine resistance4.2.4.3—State, qualitatively, the relationship4.2.4.4—And explain the current–voltage graphs4.2.4.5—Following relationship for a metallic

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.

Question 4

[Maximum number: 3]

On Fig. 6.1, sketch the current-voltage graph of a filament lamp and explain its shape.

Fig. 6.1

Fig. 6.1

explanation

Question 5

[Maximum number: 4]

A cylinder is made of modelling clay. The modelling clay is an electrical conductor.
Fig. 8.1 shows the cylinder.

Fig. 8.1

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.

Fig. 8.2

Fig. 8.2

The resistance of P is 4.0Ω4.0 \Omega. The current in P is 1.5 A .

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 =

[Total: 9]

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