The velocity of electromagnetic radiation in a medium of permittivity ${\epsilon }_0$ and permeability ${\mu }_0$ is given by:

1.  $\sqrt{\frac{{\mathrm{\epsilon }}_{\mathrm{o}}}{{\mathrm{\mu }}_{\mathrm{o}}}}$

2.  $\sqrt{{\mathrm{\mu }}_{\mathrm{o}}{\mathrm{\epsilon }}_{\mathrm{o}}}$

3.  $\frac{1}{\sqrt{{\mathrm{\mu }}_{\mathrm{o}}{\mathrm{\epsilon }}_{\mathrm{o}}}}$

4.  $\sqrt{\frac{{\mathrm{\mu }}_{\mathrm{o}}}{{\mathrm{\epsilon }}_{\mathrm{o}}}}$

The electric and magnetic fields of an electromagnetic wave are:

Which colour of the light has the longest wavelength?

A parallel plate capacitor of capacitance $20~\mu\text{F}$ is being charged by a voltage source whose potential is changing at the rate of $3~\text{V/s}.$ The conduction current through the connecting wires, and the displacement current through the plates of the capacitor would be, respectively:

The electric and the magnetic fields, associated with an electromagnetic wave, propagating along the positive Z-axis, can be represented by:
1. $\left [E=E_{0}\hat{k},~B=B_{0}\hat{i} \right ]$
2. $\left [E=E_{0}\hat{j},~B=B_{0}\hat{j} \right ]$
3. $\left [E=E_{0}\hat{j},~B=B_{0}\hat{k} \right ]$
4. $\left [E=E_{0}\hat{i},~B=B_{0}\hat{j} \right ]$

Light with an energy flux of $25\times10^4$ Wm^–2 falls on a perfectly reflecting surface at normal incidence. If the surface area is $15$ cm², the average force exerted on the surface is:
1. $1.25\times 10^{-6}$ N
2. $2.50\times 10^{-6}$ N
3. $1.20\times 10^{-6}$ N
4. $3.0\times 10^{-6}$ N

Out of the following options which one can be used to produce a propagating electromagnetic wave?

A $100~\Omega$ resistance and a capacitor of $100~\Omega$ reactance are connected in series across a $220~\text{V}$ source. When the capacitor is $50\%$ charged, the peak value of the displacement current is:
1. $2.2~\text{A}$
2. $11~\text{A}$
3. $4.4~\text{A}$
4. $11\sqrt{2}~\text{A}$