Physics 9702 · AS & A Level · Potential difference and power
Potential difference and power — practice question
Fig. 6.1 shows a battery joined in series to a resistor $R$ with resistance $5.0\,\Omega$. The battery has electromotive force (e.m.f.) $9.0\,\text{V}$ and internal resistance $r$. The potential difference (p.d.) across its terminals is $6.9\,\text{V}$.
(a)[2]
Use energy ideas to explain why the p.d. across the battery is different from the e.m.f. of the battery.
(b(i))[2]
Calculate the current in the circuit.
(b(ii))[2]
Calculate the internal resistance $r$.
(c(i))[2]
Calculate the battery’s total power output in the circuit.
(c(ii))[2]
Calculate the efficiency.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “e.m.f. is the energy supplied per unit charge” …