Question

In an electromagnetic wave, the direction of propagation is in the direction of

• A. $\mathrm{E}$
• B. $\mathrm{B}$
• C. $\mathrm{E}\times \mathrm{B}$
• D. None of these

Answer 1

The correct option is C

$\mathrm{E}\times \mathrm{B}$

Explanation for the correct option:

Option(C):

1. An electromagnetic wave is known to be a traveling wave that has time-varying electric field and magnetic fields, which are perpendicular to each other and to the direction of propagation.
2. The direction of propagation of the electromagnetic wave always tends to be perpendicular to the plane in which the electric field (E) and magnetic field(B) lie.
3. Thus, the direction of propagation of the electromagnetic wave can be given as: $\mathrm{E}\mathrm{x}\mathrm{B}$

Explanation for the incorrect option:

Option(A):

1. The direction of propagation of the electromagnetic wave tends to be perpendicular to the plane of not only electric field (E) but the magnetic field(B) as well.
2. Hence, the given option does not completely coincide with the correct concept.

Option(B):

1. The direction of propagation of the electromagnetic wave tends to be perpendicular to the plane of not only the magnetic field(B) but the electric field (E) as well.
2. Hence, the given option does not completely represent the correct concept.

Hence, in an electromagnetic wave, the direction of propagation is in the direction of $\mathrm{E}\times \mathrm{B}$. Hence, option C is correct.