Question

An em wave is propagating in a medium with a velocity $\vec{v}=v\hat{i}$ . 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

• A. - x direction
• B. - z direction
• C. - y direction
• D. + z direction

Answer 1

Answer: (D)

$\vec{E}\times \vec{B}=\vec{V}$
$(E\hat{j})\times (\vec{B})=V\hat{i}$
So, $\vec{B}=B\hat{k}$
Direction of propagation is along $+z$ direction.