Physics (AS & A Level) · Oct / Nov 2019 · Paper 12 · Question 31

When the current in a wire is 5.0 A, the average drift speed of the conduction electrons in the wire is 7.4 × 10⁻⁴ m s⁻¹. Which row gives a possible cross-sectional area and number of conduction electrons per unit volume for this wire?

1. A7.2 × 10⁻⁷ ; 1.2 × 10²⁸
2. B7.2 × 10⁻⁷ ; 5.9 × 10²⁸
3. C2.3 × 10⁻⁶ ; 7.3 × 10²⁶
4. D2.3 × 10⁻⁶ ; 3.7 × 10²⁷

As printed in the paper