The energy required to charge a parallel plate condenser of plate separation $d$ and plate area of…
The energy required to charge a parallel plate condenser of plate separation $d$ and plate area of cross-section A such that the uniform electric field between the plates is E, is
$\frac{1}{2} \varepsilon_0 E^2 A d$
$\frac{1}{2} \varepsilon_0 E^2 / A . d$
$\varepsilon_0 E^2 / A d$
$\varepsilon_0 \mathrm{E}^2 A d$
Solution
$\text {Energy required }=\frac{1}{2} C V^2=\frac{1}{2} \varepsilon_0 E^2 \mathrm{Ad}$