Physics (AS & A Level) · May / June 2025 · Paper 13 · Question 36

A battery has an e.m.f. E and internal resistance r. The battery delivers a current I to a variable resistor and the p.d. across its terminals is V. The variable resistor is adjusted so that I increases. Why does V decrease?

1. AThe e.m.f. E decreases.
2. BThe internal resistance r increases.
3. CThe p.d. across r increases.
4. DThe resistance of the variable resistor increases.

As printed in the paper