Physics (AS & A Level) · May / June 2016 · Paper 13 · Question 36

A 100 cm potentiometer wire QT is connected in series with a 2.00 V cell. Another circuit, consisting of a 2.00 V cell in series with resistors of resistance 4.00 Ω and 6.00 Ω, is set up alongside the potentiometer. Connections PQ and RS are then made so that the potential difference (p.d.) across the 4.00 Ω resistor is balanced against the p.d. across a length L of potentiometer wire. Both cells have negligible internal resistance. What is the balance length L?

1. A0 cm
2. B40 cm
3. C60 cm
4. D100 cm

As printed in the paper