JEE Main 2025 — Electromagnetic Waves Question with Solution

The unit of the expression $\sqrt{\frac{2I}{{\epsilon }_{0}c}}$ can be determined by exploring the relationship between intensity ($I$) and the electric field ($E_0$) in an electromagnetic wave.

The intensity of an electromagnetic wave is given by:

$I=\frac{1}{2}{\epsilon }_0{E}_0^2\times c$

From this equation, we can solve for the electric field $E_0$:

$E_0=\sqrt{\frac{2I}{{\epsilon }_{0}c}}$

The symbol $E_0$ represents the electric field, which is measured in units of Newtons per Coulomb (N/C). Therefore, the unit of the expression $\sqrt{\frac{2I}{{\epsilon }_{0}c}}$ is also $N/C$.

Thus, the expression $\sqrt{\frac{2I}{{\epsilon }_{0}c}}$ has units of $N/C$.