If $c $ is the speed of electromagnetic waves in vacuum, its speed in a medium of dielectric constant $K$ and relative permeability ${\mu _r}$ is

A plane electromagnetic wave, has frequency of $2.0 \times 10^{10}\, Hz$ and its energy density is $1.02 \times 10^{-8}\, J / m ^{3}$ in vacuum. The amplitude of the magnetic field of the wave is close to$....nT$

$\left(\frac{1}{4 \pi \varepsilon_{0}}=9 \times 10^{\circ} \frac{ Nm ^{2}}{ C ^{2}}\right.$ and speed of $1 ight$ $\left.=3 \times 10^{8}\, ms ^{-1}\right)$

A light beam is described by $E=800 \sin \omega\left(t-\frac{x}{c}\right)$

An electron is allowed to move normal to the propagation of light beam with a speed of $3 \times 10^{7}\;{ms}^{-1}$. What is the maximum magnetic force exerted on the electron ?

Electromagnetic waves travel in a medium which has relative permeability $1.3$ and relative permittivity $2.14$. Then the speed of the electromagnetic wave in the medium will be

The magnetic field of a plane electromagnetic wave is given by

$\vec B\, = {B_0}\hat i\,[\cos \,(kz - \omega t)]\, + \,{B_1}\hat j\,\cos \,(kz - \omega t)$ where ${B_0} = 3 \times {10^{-5}}\,T$ and ${B_1} = 2 \times {10^{-6}}\,T$. The rms value of the force experienced by a stationary charge $Q = 10^{-4} \,C$ at $z = 0$ is closet to

In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of $2.0 \times 10^{10}\; Hz$ and amplitude $48\; Vm ^{-1}$

$(a)$ What is the wavelength of the wave?

$(b)$ What is the amplitude of the oscillating magnetic field?

$(c)$ Show that the average energy density of the $E$ field equals the average energy density of the $B$ field. $\left[c=3 \times 10^{8} \;m s ^{-1} .\right]$