JEE Main 2025 Apr 7 Shift 2, Physics Q3: Electromagnetic Waves

The time-averaged intensity of an electromagnetic wave in vacuum is $I=\frac{1}{2}{ϵ}_0{E}_0^{2}c$, where $E_0$ is the peak electric field amplitude.

Rearranging for $E_0$: $E_0=\sqrt{\frac{2I}{{ϵ}_{0}c}}$.

Since the quantity under the root has the dimensions of the electric field, its SI unit is volts per metre, equivalently newtons per coulomb (NC${}^{-1}$).