Two capacitors of capacitances 
and 
, and a resistor of resistance 
, are connected into the circuit shown below.
The battery has an e.m.f. of 
.
Show that the combined capacitance of the two capacitors is 
.
The two-way switch S is initially at position X so that the capacitors are fully charged. Use the information in (a) to calculate the total energy stored in the two capacitors.
.
