Electromagnetic Waves · Question 3

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 correct 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 true but (R) is false
4. (A) is false but (R) is true

A magnetic field vector in an electromagnetic wave is represented by B=B0 (2 t- 2 x ) j. Its associated electric field vector is .

1. E=- B0 (2 t- 2 x ) k
2. E=- B0 (2 t- 2 x ) i
3. E= B0 (2 t- 2 x ) k
4. E= B0 (2 t- 2 x ) i

An electromagnetic wave travelling in x-direction is described by field equation Ey=300 (t- xc ). If the electron is restricted to move in y-direction only with speed of 1.5 106 m/s then ratio of maximum electric and magnetic forces acting on the electron is .

1. 200
2. 150
3. 400
4. 300

An electromagnetic wave travels in free space along the x-direction. At a particular point in space and time, B=2 10-7 j T is associated with this wave. The value of corresponding electric field E at this point is V/m.

1. 60 k
2. -60 k
3. 30 k
4. -600 k

The electric field of an electromagnetic wave travelling through a medium is given by E(x, t) = 25 (2.0 1015 t - 107 x ) n then the refractive index of the medium is . (All given measurements are in SI units)

1. 2
2. 1.2
3. 1.5
4. 1.7

A plane electromagnetic wave is moving in free space with velocity c = 3 108 m/s and its electric field is given as E = 54 (kz - t) j V/m, where j is the unit vector along y-axis. The magnetic field vector B of the wave is :

1. -1.8 10-7 (kz - t) i T
2. +1.8 10-7 (kz - t) i T
3. 1.4 10-7 (kz - t) k T
4. 1.4 10-7 (kz - t) i T

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

1. A-IV, B-II, C-I, D-III
2. A-IV, B-III, C-I, D-II
3. A-IV, B-I, C-II, D-III
4. A-II, B-IV, C-III, D-I

A point source is kept at the center of a spherically enclosed detector. If the volume of the detector is increased by 8 times, the intensity will

1. increase by 64 times
2. decrease by 4 times
3. decrease by 8 times
4. increase by 8 times

Match List-I with List-II. Choose the correct answer from the options given below :

1. A-I, B-IV, C-III, D-II
2. A-II, B-III, C-IV, D-I
3. A-IV, B-I, C-II, D-III
4. A-II, B-III, C-I, D-IV

The equation of the electric field of an electromagnetic wave propagating through free space is given by : E = 377 (6.27 103 t - 2.09 10-5 x) N/C The average intensity of the electromagnetic wave is ( 1 ) W/m2. The value of α is . (Take 0 0 = 377 in SI units )