(a)[1]
State expressions, using $C$ and $V$, for the charge $Q$ on one plate and for the energy $E$ stored in the capacitor.
(b(i))[1]
The capacitor charged in (a) is now detached from the supply. At first, the plates are separated by a distance $L$. They are then brought closer by a distance $D$, as shown in Fig. 6.2. State an expression, in terms of $C$, $V$, $L$ and $D$, for the new capacitance $C_N$.
(b(ii))[1]
State an expression, in terms of $C$, $V$, $L$ and $D$, for the new charge $Q_N$ on one plate.
(b(iii))[1]
State an expression, in terms of $C$, $V$, $L$ and $D$, for the new p.d. $V_N$ across the plates.
(c)[1]
Explain whether making the plate separation in (b) smaller causes the energy stored in the capacitor to increase or decrease.