Question

An electro-magnetic wave is propagating in a medium with a velocity $\overrightarrow{v}=v\hat{i}$ . The instantaneous oscillating electric field of this electromagnetic wave is along $+y$ axis. Then, the direction of oscillating magnetic field of the electromagnetic wave will be along

• A. –$z$ direction
• B. +$z$ direction
• C. –$y$ direction
• D. –$x$ direction

Answer 1

The correct option is B +$z$ direction

Direction of propagation of wave is given by
$\overrightarrow{v}=\overrightarrow{E}\times \overrightarrow{B}$. Since direction of propagation of wave is in +$x$ direction and oscillation of electric field is in $+y$ direction, magnetic field should oscillate in $+z$ direction.