Electromagnetic Waves · Question 12

When light propagates through a material medium of relative permittivity r and relative permeability r, the velocity of light, v is given by (c-velocity of light in vacuum)

1. v = c
2. v = r r
3. v = r r
4. v = c r r

The magnetic field of a plane electromagnetic wave is given by B = 3 10-8 (1.6 103 x + 48 1010 t) j, then the associated electric field will be :

1. 9 (1.6 103 x + 48 1010 t) k V/m
2. 3 10-8 (1.6 103 x + 48 1010 t) i V/m
3. 3 10-8 (1.6 103 x + 48 1010 t) i V/m
4. 9 (1.6 103 x - 48 1010 t) k V/m

The ratio of the magnitude of the magnetic field and electric field intensity of a plane electromagnetic wave in free space of permeability 0 and permittivity 0 is (Given that c - velocity of light in free space)

1. 0 0c
2. c
3. 1c
4. c 0 0

A capacitor of capacitance 'C', is connected across an ac source of voltage V, given by V = V0 t The displacement current between the plates of the capacitor, would then be given by :

1. Id = V0 C t
2. Id = V0 C t
3. Id = V0 C t
4. Id = V0 C t

For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?

1. - j + k, - j + k
2. j + k, j + k
3. - j + k, - j - k
4. j + k, - j - k

The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is : (c = speed of electromagnetic waves)

1. 1 : 1
2. 1 : c
3. 1 : c2
4. c : 1

Light with an average flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence having surface area 20 cm2. The energy received by the surface during time span of 1 minute is :

1. 12 103 J
2. 24 103 J
3. 48 103 J
4. 10 103 J

Which colour of the light has the longest wavelength?

1. blue
2. violet
3. red
4. green

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

1. zero, zero
2. zero, 60
3. 60 , 60
4. 60 , zero

An EM wave is propagating in a medium with a velocity v = v i. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along

1. −z direction
2. +z direction
3. −y direction
4. −x direction