Two capacitors A and B are connected into the circuit shown in the figure below.
Capacitor A has capacitance 
and capacitor B has capacitance 
. The electromotive force (e.m.f.) of the cell is 
. The two-way switch S is initially at position X, and capacitor B is initially uncharged.
State, in terms of and , expression for the initial energy 
stored in capacitor A.
The two-way switch S is now moved to position Y.
Show that the final potential difference (p.d.) 
across capacitor B is given by
Explain your reasoning.
Determine an expression, in terms of and , for the decrease 
in the total energy that is stored in the capacitors as a result of the change of the position of the switch.
and 
in the circuit is the sum of the charges 
and 
in the capacitors A and B respectively.
