Physics (AS & A Level) · May / June 2020 · Paper 12 · Question 33

The number density of free electrons in copper is 8.0 × 10^28 m^–3. A copper wire has diameter 0.42 mm. What is the average drift speed of the free electrons in the wire when the current in the wire is 0.57 A?

1. A8.0 × 10^–11 m s^–1
2. B3.2 × 10^–10 m s^–1
3. C8.0 × 10^–5 m s^–1
4. D3.2 × 10^–4 m s^–1

As printed in the paper