When $\mu_r$ and $\epsilon_r$ are the relative permeability and relative permittivity (dielectric constant) respectively,the refractive index is given by:

$A$ plane electromagnetic wave of frequency $25 \; MHz$ travels in free space along the $x$-direction. At a particular point in space and time,$\vec{E} = 6.3 \hat{j} \; V/m$. What is $\vec{B}$ at this point?

Radio waves and visible light in vacuum have

The sun delivers $10^{3} \,W m^{-2}$ of electromagnetic flux on the Earth's surface. The total power that is incident on a roof of dimensions $6 \,m \times 30 \,m$ is . . . . . . .

Which of the following do not require a medium for transmission?

The quantities $x = \frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$,$y = \frac{E}{B}$,and $z = \frac{l}{CR}$ are defined,where $C$ is capacitance,$R$ is resistance,$l$ is length,$E$ is electric field,$B$ is magnetic field,and $\varepsilon_{0}, \mu_{0}$ are free space permittivity and permeability respectively. Then: