Q 12-08-159JEE MainJEE Main 2021 (18 Mar, Shift 2)Easy
A plane electromagnetic wave propagating along $y$-direction can have the following pair of electric field $(\vec E)$ and magnetic field $(\vec B)$ components.
Answer: (C) $E_x, B_z$ or $E_z, B_x$
Both $\vec E$ and $\vec B$ must be perpendicular to the direction of propagation ($y$) and to each other. So the possible pairs are $(E_x, B_z)$ and $(E_z, B_x)$, with signs chosen so that $\vec E\times\vec B$ points along $+y$.
Solution by Sreeraj P, M.Sc Physics