A capacitor, a battery of electromotive force (e.m.f.) 
, a resistor 
, and a two-way switch are connected in the circuit shown in the figure below.
The switch is initially in position S. When the capacitor is fully charged, the switch is moved to position T so that the capacitor discharges. At time 
after the switch is moved the charge on the capacitor is 
. The variation with of 
(Q/
) is shown in the graph below.
Show that the capacitance of the capacitor is 
.
Calculate the energy stored in the capacitor at time 
.
.
