If $10 \%$ of the power of a $(100 \pi) \ W$ light bulb is converted to visible radiation,then the average intensity of visible radiation at a distance of $10 \ m$ is (in $W \ m^{-2}$)

$A$ light beam is described by $E = 800 \sin \omega (t - x/c)$. An electron is allowed to move normal to the propagation of the light beam with a speed of $3 \times 10^{7} \text{ m/s}$. What is the maximum magnetic force exerted on the electron?

If the magnetic field of a light wave oscillates parallel to the $y-$ axis and is given by $B_y = B_m \sin(kz - \omega t)$,the direction of wave travel and the axis along which the electric vector oscillates are:

Given below are two statements:
Statement $I$: $A$ time-varying electric field is a source of a changing magnetic field and vice-versa. Thus,a disturbance in an electric or magnetic field creates $EM$ waves.
Statement $II$: In a material medium,the $EM$ wave travels with speed $v = \frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$.
In the light of the above statements,choose the correct answer from the options given below:

Electromagnetic waves travel in a medium with a speed of $1.5 \times 10^8 \ m/s$. The relative permeability of the medium is $2.0$. The relative permittivity will be:

The $rms$ value of the electric field of the light coming from the sun is $720 \ N \ C^{-1}$. The average energy density of the electromagnetic wave is $...... \ J \ m^{-3}$.