Question

The velocity of electromagnetic wave is parallel to :-

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

Answer 1

Answer: (B)

According to poynting theorem, direction of wave is given by:
$\hat{S}=\hat{E}\times \hat{B}$
or velocity of em wave is parallel to $\vec{E}\times \vec{B}$