If \(\varepsilon_0~\text{and}~\mu_0\) represent the permittivity and permeability of vacuum and \(\varepsilon~\text{and}~\mu\) represent the permittivity and permeability of the medium, the refractive index of the medium is given by:

1.	\(\sqrt{\dfrac{\varepsilon_0 \mu_0}{\varepsilon \mu}}\)	2.	\(\sqrt{\dfrac{\varepsilon \mu}{\varepsilon_0 \mu_0}}\)
3.	\(\sqrt{\dfrac{\varepsilon }{\varepsilon_0 \mu_0}}\)	4.	\(\sqrt{\dfrac{\varepsilon_0 \mu_0}{\varepsilon }}\)

The average energy - density of electromagnetic wave given by E = (50 N/C) sin($\omega t-kx)$ will be nearly

1. ${10}^{-8} J/m^3$

2. ${10}^{-7} J/m^3$

3. ${10}^{-6} J/m^3$

4. ${10}^{-5} J/m^3$

A parallel plate capacitor with plate area A and separation between the plates d, is charged by a constant current i.  Consider a plane surface of area A/2 parallel to the plates and drawn symmetrically between the plates. The displacement current through this area is

(1) i

(2) i/2

(3) i/4

(4) i/8

A plane electromagnetic wave propagating in the x-direction has wavelength of 60 mm. The electric field is in the y-direction and its maximum magnitude is 33 V/$m^{-1}$. The equation for the electric field as function of x and t is

(1) 11 sin $\mathrm{\pi }$(t - x/c)

(2) 33 sin $\mathrm{\pi }\times {10}^{10}$ (t - x/c)

(3) 33 sin $\mathrm{\pi }$(t - x/c)

(4) 11 sin $\mathrm{\pi }\times {10}^{11}$(t - x/c)

If ${\mu }_0$ be the permeability and $K_0$ the dielectric constant of a medium, its refractive index is given by

(1) $\frac{1}{\sqrt{{\mu }_0{K}_0}}$

(2) $\frac{1}{{\mu }_0{K}_0}$

(3) $\sqrt{K_0}$

(4) ${\mu }_0{K}_0$

A plane electromagnetic wave $E_z=100 \cos (6\times {10}^{8}t+4x) V/m$ propagates in a medium of dielectric constant

(1) 1.5

(2) 2.0

(3) 2.4

(4) 4.0

A plane electromagnetic wave of frequency 40 MHz travels in free space in the x-direction. At some point and at some instant, the electric field $\overrightarrow{E}$ has its maximum value of 750 N/C in y-direction. The wavelength of the wave is

(1) 3.5 m

(2) 5.5 m

(3) 7.5 m

(4) 9.5 m

In a plane electromagnetic wave propagating in space has an electric field of amplitude $9\times {10}^3$ V/m, then the amplitude of the magnetic field is

(1) $2.7\times {10}^{12} T$

(2) $9.0\times {10}^{-3} T$

(3) $3.0\times {10}^{-4} T$

(4) $3.0\times {10}^{-5} T$