Question

A capacitor of capacitance $10\mu F$ is charged using a battery of emf 2 V. How much energy does the battery supply to the circuit in fully charging the capacitor.

Answer 1

Energy supplied by battery
Charge supply by battery = Charge on capacitor = Q = CV

Energy supplied by battery = Work done by the battery = QV = (CV) (V)

$=C{V}^2$
$=10\mu F\times 4V$
$=40\mu J$

Thus, energy supplied by the battery is $=40\mu J$.

Hence the correct option is (B).