If the potential of a capacitor having capacity 6μF is increased from 10 V to 20 V, then increase in its energy will be ?

If the potential of a capacitor having capacity 6μF is increased from 10 V to 20 V, then increase in its energy will be ?

\( \text{(a)} \ 4 \times 10^{-4} \, \text{J} \)

\( \text{(b)} \ 4 \times 10^{-4} \, \text{J} \)

\( \text{(c)} \ 9 \times 10^{-4} \, \text{J} \)

\( \text{(d)} \ 12 \times 10^{-6} \, \text{J} \)

Answer :  \( \text{(c)} \ 9 \times 10^{-4} \, \text{J} \)

\( \Delta U = U_f - U_i \)

\( = \frac{1}{2} C V^2 - \frac{1}{2} C V^2 \)

\( = \frac{1}{2} \times 6 \times 300 \times 10^{-6} \)