Physics · May / June 2019 · Paper 12 · Question 32

The diagram shows a car ignition switch and starter motor. The ignition switch is in a circuit with long, thin wires. The starter motor is in a circuit with short, thick wires. What is the explanation for the choice of wires?

1. AEach circuit needs to contain the same total mass of wire.
2. BThicker wires heat up more quickly when the relay is switched on.
3. CThin wires have lower resistances.
4. DThe ignition switch circuit carries a smaller current than the starter motor circuit.

As printed in the paper