The amplitude of the electric field associated with a light beam of intensity $\frac{15}{\pi} \text{ W m}^{-2}$ is (in $\text{ N C}^{-1}$)

Which of the following statements is false regarding the properties of electromagnetic waves?

$A$ plane polarized monochromatic $EM$ wave is travelling in a vacuum along the $z$-direction such that at $t = t_1$,it is found that the electric field is zero at a spatial point $z_1$. The next zero that occurs in its neighborhood is at $z_2$. The frequency of the electromagnetic wave is:

$A$ laser beam has intensity $17.7 \times 10^{14} \ W/m^2$. The amplitude of the electric field is
[Use $\epsilon_0 = 8.85 \times 10^{-12} \ C^2 / (N \cdot m^2)$]

The electric field and magnetic field associated with an electromagnetic $(e.m.)$ wave,propagating along the $-z$ axis,can be represented by:

In an $E.M.$ wave,the average energy density is associated with