Q 12-08-036JEE MainJEE Main 2026 (2 Apr, Shift 2)Easy
An electromagnetic wave travels in free space along the $x$-direction. At a particular point in space and time, $\vec B=2\times10^{-7}\hat j$ T is associated with this wave. The value of corresponding electric field $\vec E$ at this point is ______ V/m.
Answer: (B) $-60\,\hat k$
Magnitude: $E=cB=3\times10^{8}\times2\times10^{-7}=60$ V/m.
Direction: $\vec E\times\vec B$ points along the direction of travel, $+\hat i$. With $\vec B$ along $\hat j$: $(-\hat k)\times\hat j=\hat i$, so $\vec E$ is along $-\hat k$.
$\vec E=-60\,\hat k$ V/m
Solution by Sreeraj P, M.Sc Physics