Work done in placing a charge of $8\times {10}^{-18}$ C on a condenser of capacity 100 $\mathrm{\mu }$F is

Here, $\mathrm{q}=8\times {10}^{-18}\mathrm{C},\mathrm{C}=100\mathrm{\mu F}={10}^{-4} \mathrm{F}$

Potential, $\mathrm{V}=\frac{\mathrm{q}}{\mathrm{C}}=\frac{8\times {10}^{-18}}{{10}^{-4}}=8\times {10}^{-14} \mathrm{V}$

Energy stored in the capacitor $=\frac{1}{2}\mathrm{qV}=\frac{1}{2}\times 8\times {10}^{-18}\times 8\times {10}^{-14}$

                   $=32\times {10}^{-32} \mathrm{J}$

But work done = 64 x10^-32  joule