Physics (AS & A Level) · May / June 2026 · Paper 13 · Question 34

A straight copper wire, of diameter 4.2 × 10⁻⁴ m, has a number density of free electrons of 8.5 × 10²⁸ m⁻³. In a given time interval, a charge of 0.15 C moves through the wire. What is the average displacement of the free electrons along the wire in this time interval?

1. A3.3 × 10⁻⁸ m
2. B2.0 × 10⁻⁵ m
3. C8.0 × 10⁻⁵ m
4. D2.5 × 10⁻⁴ m

As printed in the paper