Q 12-08-087JEE MainJEE Main 2023 (25 Jan, Shift 1)Easy
An electromagnetic wave is transporting energy in the negative $z$ direction. At a certain point and certain time the direction of electric field of the wave is along positive $y$ direction. What will be the direction of the magnetic field of the wave at that point and instant?
Answer: (A) Positive direction of $x$
The wave travels along $\vec E\times\vec B$. With $\vec E$ along $+\hat j$ we need $\hat j\times\hat B=-\hat k$, which holds for $\hat B=+\hat i$ (since $\hat j\times\hat i=-\hat k$).
Solution by Sreeraj P, M.Sc Physics