Which one of the following statements is not the property of light?

$A$ sky wave with a frequency of $55 \text{ MHz}$ is incident on the $D$-region of the ionosphere at an angle of $45^\circ$. What is the angle of refraction? (The electron density in the $D$-region is $400 \text{ electrons/cm}^3$).

The speed of an electromagnetic wave in a vacuum depends upon the source of radiation.

In a plane electromagnetic wave,the average value of ....... is zero.

The electric and magnetic fields associated with an electromagnetic wave propagating along the $Z$-axis can be represented by:

Suppose that the electric field amplitude of an electromagnetic wave is $E_{0}=120 \text{ NC}^{-1}$ and its frequency $f=50 \text{ MHz}$. Then,which of the following values is incorrectly computed?