Physics (AS & A Level) · Oct / Nov 2019 · Paper 12 · Question 37

The diagram shows a variable resistor R and two fixed resistors connected in series in a circuit to act as a potential divider. The cell of electromotive force (e.m.f.) 6.0 V has negligible internal resistance. A cell of e.m.f. 2.0 V and a galvanometer are connected into the potential divider. The resistance of R is varied until the galvanometer reads zero. What is the resistance of resistor R?

1. A3.0 Ω
2. B5.0 Ω
3. C8.0 Ω
4. D18 Ω

As printed in the paper