A parallel plate capacitor has a uniform electric field ‘ E’ in the space between the plates. If the distance between the plates is ‘d’ and the area of each plate is ‘A’, the energy stored in the capacitor is : (ε₀=permittivity of free space)

To find the energy stored in a parallel plate capacitor, we can express it in terms of the uniform electric field $E$ between its plates, the distance $d$ between the plates, and the area $A$ of each plate.

First, let's recall the standard formula for the energy $U$ stored in a capacitor:
$U=\frac{1}{2}C{V}^2$
where $C$ is the capacitance of the capacitor and $V$ is the potential difference between the plates.

For a parallel plate capacitor with plate area $A$ and separation $d$, the capacitance $C$ in free space is given by:
$C=\frac{{\epsilon }_{0}A}{d}$
where ${\epsilon }_0$ is the permittivity of free space.

The relationship between the uniform electric field $E$ and the potential difference $V$ over the distance $d$ is:
$V=E·d$

Substituting the expressions for $C$ and $V$ back into the energy equation:
$U=\frac{1}{2}\left(\frac{{\epsilon }_{0}A}{d}\right){\left(Ed\right)}^2$
Simplifying this expression:
$U=\frac{1}{2}\left(\frac{{\epsilon }_{0}A}{d}\right)\left(E^2{d}^2\right)$
$U=\frac{1}{2}{\epsilon }_0{E}^{2}Ad$

Thus, the energy stored in the capacitor is $\frac{1}{2}{\epsilon }_0{E}^{2}Ad$.

The correct option is 1/2 ε₀E²Ad.