Physics (AS & A Level) · May / June 2018 · Paper 13 · Question 31

A cell of electromotive force (e.m.f.) E and internal resistance r is connected to an external resistor of resistance R, as shown. What is the power dissipated in the external resistor?

1. A\frac{E^2(R+r)}{R^2}
2. B\frac{E^2R}{(R+r)^2}
3. C\frac{E^2(R+r)}{r^2}
4. D\frac{E^2r}{(R+r)^2}

As printed in the paper