Physics (AS & A Level) · Oct / Nov 2020 · Paper 13 · Question 38

A power supply and a solar cell are compared using the potentiometer circuit shown. The potentiometer wire PQ is 100.0 cm long and has a resistance of 5.00 Ω. The power supply has an e.m.f. of 2.000 V and the solar cell has an e.m.f. of 5.00 mV. Which resistance R must be used so that the galvanometer reads zero when PS = 40.0 cm?

1. A395 Ω
2. B405 Ω
3. C795 Ω
4. D805 Ω

As printed in the paper