Electromagnetic Waves · Question 15

A laser beam has intensity of 4.0 1014 W/m2. The amplitude of magnetic field associated with beam is T. (Take 0 = 8.85 10-12 C2/Nm2 and c = 3 108 m/s)

1. 1.83
2. 2.0
3. 5.5
4. 18.3

If , E and t represent the free space permittivity, electric field and time respectively, then the unit of Et will be :

1. Am
2. A/m
3. A/m2
4. Am2

The electric field in a plane electromagnetic wave is given by : Ey = 69 [0.6 103x - 1.8 1011t ] V/m. The expression for magnetic field associated with this electromagnetic wave is T.

1. Bz = 2.3 10-7 [0.6 103x - 1.8 1011t ]
2. Bz = 2.3 10-7 [0.6 103x + 1.8 1011t ]
3. By = 2.3 10-7 [0.6 103x - 1.8 1011t ]
4. By = 69 [0.6 103x + 1.8 1011t ]

An electromagnetic wave of frequency 100 MHz propagates through a medium of conductivity, = 10 mho/m. The ratio of maximum conduction current density to maximum displacement current density is . [Take 14 0 = 9 109 N m2/C2]

If 0 denotes the permittivity of free space and E is the flux of the electric field through the area bounded by the closed surface, then dimensions of ( 0 d Edt ) are that of :

1. electric charge
2. electric field
3. electric current
4. electric potential

The unit of 2I 0 c is : (I = intensity of an electromagnetic wave, c = speed of light)

1. Vm
2. NC-1
3. NC
4. Nm

If an optical medium possesses a relative permeability of 10 and relative permittivity of 10.0885, then the velocity of light is greater in vacuum than that in this medium by times. ( 0 = 4 10-7 H/m, 0 = 8.85 10-12 F/m, c = 3 108 m/s)

The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed 2 m away from it, is

1. 3 10-8 Pascals
2. 0
3. 1.5 10-8 Pascals
4. 6 10-8 Pascals

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below :

1. Both (A) and (R) are true and (R) is the correct explanation of (A)
2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
3. (A) is false but (R) is true
4. (A) is true but (R) is false

Due to presence of an em-wave whose electric component is given by E = 100 ( t - kx) NC-1 a cylinder of length 200 cm holds certain amount of em-energy inside it. If another cylinder of same length but half diameter than previous one holds same amount of em-energy, the magnitude of the electric field of the corresponding em-wave should be modified as

1. 50 ( t - kx) NC-1
2. 400 ( t - kx) NC-1
3. 200 ( t - kx) NC-1
4. 25 ( t - kx) NC-1