Physics 9702 · AS & A Level · Energy stored in a capacitor
Energy stored in a capacitor — practice question
As illustrated in Fig. 6.1, an initially uncharged capacitor is placed in series with a battery, a switch and a resistor. The battery has e.m.f. $9.0\,\text{V}$ and negligible internal resistance. The capacitance of the capacitor is $4700\,\mu\text{F}$. The switch is closed at time $t = 0$. Over the interval from $t = 0$ to $t = 4.0\,\text{s}$, the charge that flows through the resistor is $22\,\text{mC}$.
(a(i))[2]
Calculate the energy transferred by the battery over the interval from $t = 0$ to $t = 4.0\,\text{s}$.
(a(ii).1)[2]
Determine, for the capacitor at time $t = 4.0\,\text{s}$, the potential difference $V$ across it.
(a(ii).2)[2]
Determine, for the capacitor at time $t = 4.0\,\text{s}$, the energy stored in it.
(b)[1]
Suggest why your answers in (a)(i) and (a)(ii) part 2 are different.
(a(ii))[2]
the energy held in the capacitor.\n\nenergy $=$ ........................................ J
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct use of $E = EQ$” …