Physics (AS & A Level) · Oct / Nov 2017 · Paper 12 · Question 33

Two copper wires are joined together and carry a current, as shown. Wire P has diameter $d$ and wire Q has diameter $2d$. What is the ratio $\dfrac{\text{average drift speed of the free electrons in wire P}}{\text{average drift speed of the free electrons in wire Q}}$?

1. A$\dfrac{1}{4}$
2. B$\dfrac{1}{2}$
3. C2
4. D4

As printed in the paper