Physics (AS & A Level) · Oct / Nov 2020 · Paper 11 · Question 34

A cable of length L consisting of two wires is used to connect a 12.0 V power supply of negligible internal resistance to a lamp, as shown. The potential difference across the lamp is 10.5 V. The current in the wire is 2.50 A. Each wire is made of metal of resistivity 1.70 × 10⁻⁸ Ω m and has a cross-sectional area of 6.00 × 10⁻⁷ m². What is the length L of the cable?

1. A10.6 m
2. B21.2 m
3. C29.4 m
4. D58.8 m

As printed in the paper