Question

Which one of the following is the property of a monochromatic, plane electromagnetic wave in free space ?

​​​​​​​$[$1 Mark$]$

• A. Electric and magnetic fields have a phase difference of $\frac{\pi }{2}$.
• B. The energy contribution of both electric and magnetic fields are equal.
• C. The direction of propagation is in the direction of $\overrightarrow{B}\times \overrightarrow{E}$
• D. The pressure exerted by the wave is the product of its speed and energy density.

Answer 1

The correct option is B The energy contribution of both electric and magnetic fields are equal.

In electromagnetic wave, electric and Magnetic fields are in phase. Electromagnetic wave carry energy as they travel through space and this energy is shared equally by electric and magnetic fields.
The direction of the propagation of electromagnetic wave is the direction of $\overrightarrow{E}\times \overrightarrow{B}$ .
The pressure exerted by the wave is equal to its energy density.