Question

In a parallel plate capacitor, the distance between the plates is d & potential difference across plates is V. Energy stored per unit volume between the plates of capacitor is :

• A. $\frac{Q^2}{2V^2}$
• B. $\frac{1}{2}{ϵ}_0\frac{V^2}{d^2}$
• C. $\frac{1}{2}\frac{V^2}{{ϵ}_0{d}^2}$
• D. $\frac{1}{2}{ϵ}_0\frac{V^2}{d}$

Answer 1

The correct option is B $\frac{1}{2}{ϵ}_0\frac{V^2}{d^2}$

Energy stored per unit volume
$U=\frac{1}{2}{ϵ}_0{E}^2=\frac{1}{2}{ϵ}_0\left(\frac{V^2}{d^2}\right)=\frac{1}{2}{ϵ}_0\frac{V^2}{d^2}(\therefore E=\frac{V}{d})$