Figure 6.1 shows a circuit in which a $12\,\text{V}$ battery, with internal resistance $0.50\,\Omega$, supplies two identical filament lamps $L_1$ and $L_2$. The connection to the battery is made through switches $S_1$ and $S_2$. When the potential difference is $12\,\text{V}$, each lamp is rated at $48\,\text{W}$.
(a)[2]
$S_1$ is closed and $S_2$ open. State and explain whether the power transformed in $L_1$ matches $48\,\text{W}$.
(b(i))[1]
$S_2$ is now also closed. State and explain what happens to the current in $L_1$.
(b(ii))[1]
State and explain what effect this has on the resistance of $L_1$.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Lost volts are produced by internal resistance” …