JEE Main 2023 — Electromagnetic Waves Question with Solution

Maxwell’s four equations describe the electric and magnetic fields arising from distributions of electric charges and currents, and how those fields change in time.

The equations are as follows:

$$\begin{gathered} \oint \overrightarrow{E}·d\overrightarrow{A}=\frac{q}{{\epsilon }_0} ...\left(1\right) \\ \oint \stackrel{\rightharpoonup }{B}·d\stackrel{\rightharpoonup }{A}=0 ...\left(2\right) \\ \oint \stackrel{\rightharpoonup }{E}·d\stackrel{\rightharpoonup }{l}=-\frac{\partial {\varphi }_B}{\partial t} ...\left(3\right) \\ \oint \stackrel{\rightharpoonup }{B}·d\stackrel{\rightharpoonup }{l}={\mu }_{0}I ...\left(4\right) \end{gathered}$$

From the above set of equations, it is clear that only the third equation is valid for time varying field.

Hence, this is the correct option.