Physics (AS & A Level) · May / June 2024 · Paper 13 · Question 37

The diagram shows a potentiometer circuit used to compare the electromotive forces (e.m.f.), $E_1$ and $E_2$, of two cells. XY is a uniform resistance wire. The fixed resistor has resistance $R$. A sliding contact is moved along the wire XY. When the sliding contact is at position P, the galvanometer reads zero. The circuit is changed so that the galvanometer reads zero when the sliding contact is at a new position to the left of P. Which change could have been made to the circuit?

1. AThe wire XY was replaced with one of lower resistance.
2. B$E_2$ was increased.
3. C$E_1$ was decreased.
4. D$R$ was decreased.

As printed in the paper