An em wave is propagating in a medium with a velocity $\overrightarrow{\mathbf{V}}=\mathbf{V i}$. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along
(1) $-\mathrm{y}$ direction
(2) $+z$ direction
(3) $-\mathrm{z}$ direction
(4) $-\mathrm{x}$ direction

contexto.120

3 years ago

Answer is (2)

$\vec{E} \times \vec{B}=\vec{V}$

$(\mathrm{E} \hat{\mathrm{j}}) \times(\overrightarrow{\mathrm{B}})=\mathrm{V} \hat{\mathrm{i}}$

So, $\overrightarrow{\mathbf{B}}=\mathbf{B} \hat{\mathbf{k}}$

Direction of propagation is along $+z$ direction.