Electromagnetic Waves

A point light source emits E.M. waves in free space. A detector, placed at a distance of L m, measures the intensity as I0. The detector is now shifted to another location on the same spherical surface ensuring the angle between original location and new location as 45°. The measured intensity at new location will be .

1. I04
2. I0
3. I0 2
4. I02

For an electromagnetic wave propagating through vacuum, k, E and represent propagation vector, electric field and angular frequency, respectively. The magnetic field associated with this wave is represented by :

1. E k
2. k E
3. ( E k )
4. ( k E )

A displacement current of 4.0 A can be set up in the space between two parallel plates of 6 μF capacitor. The rate of change of potential difference across the plates of the capacitor is nearly 106 V/s. The value of is .

1. 0.58
2. 0.67
3. 0.82
4. 0.75

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