Question

The velocity of an electromagnetic wave is parallel to

• A. $\overrightarrow{B}\times \overrightarrow{E}$
• B. $\overrightarrow{E}\times \overrightarrow{B}$
• C. $\overrightarrow{E}$
• D. $\overrightarrow{B}$

Answer 1

The correct option is B $\overrightarrow{E}\times \overrightarrow{B}$

According to Maxwell, sinusoidal variations of electric field and magnetic field vectors in an electromagnetic wave, are at right angles to each other as well as at right angles to the direction of wave propagation.



If the electric field ($\overrightarrow{E}$) and magnetic field ($\overrightarrow{B}$) are vibrating along $y$ and $z$ directions, propagation of electromagnetic wave will be along the $x$-axis. Therefore, the velocity of the electromagnetic wave is parallel to $\overrightarrow{E}\times \overrightarrow{B}$.