Physics (AS & A Level) · Oct / Nov 2024 · Paper 13 · Question 37

A circuit contains a battery of electromotive force E and internal resistance r connected to two resistors each of resistance 2.5 Ω. The resistors are connected in parallel as shown. [circuit diagram: battery E with internal resistance r, two 2.5 Ω resistors in parallel, current 0.80 A in one resistor] The current in one of the resistors is 0.80 A. Which expression, where E is in volts and r is in ohms, gives the internal resistance r?

1. A\frac{E - 4.0}{1.6}
2. B\frac{E - 4.0}{0.80}
3. C\frac{E - 2.0}{1.6}
4. D\frac{E - 2.0}{0.80}

As printed in the paper