Electromagnetic Waves

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

A plane electromagnetic wave propagates along the + x direction in free space. The components of the electric field, E and magnetic field, B vectors associated with the wave in Cartesian frame are

1. Ex, By
2. Ey, Bx
3. Ey, Bz
4. Ez, By

A parallel plate capacitor consisting of two circular plates of radius 10 cm is being charged by a constant current of 0.15 A. If the rate of change of potential difference between the plates is 7 108 V/s then the integer value of the distance between the parallel plates is (Take, 0=9 10-12 Fm, = 227) .

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

The magnetic field of an E.M. wave is given by B = ( 32 i + 12 j )30 [ (t - zc ) ] (S.I. Units). The corresponding electric field in S.I. units is:

1. E = ( 12 i + 32 j )30c [ (t + zc ) ]
2. E = ( 12 i - 32 j )30c [ (t - zc ) ]
3. E = ( 32 i - 12 j )30c [ (t + zc ) ]
4. E = ( 34 i + 14 j )30c [ (t - zc ) ]

Arrange the following in the ascending order of wavelength ( ) : Choose the most appropriate answer from the options given below :

1. 4 < 3 < 2 < 1
2. 4 < 2 < 3 < 1
3. 3 < 4 < 2 < 1
4. 4 < 3 < 1 < 2

The electric field of an electromagnetic wave in free space is E=57 [7.5 106t-5 10-3(3x+4y) ](4 i-3 j) N/C. The associated magnetic field in Tesla is

1. B= 573 108 [7.5 106t-5 10-3(3x+4y) ]( k)
2. B= 573 108 [7.5 106t-5 10-3(3x+4y) ](5 k)
3. B=- 573 108 [7.5 106t-5 10-3(3x+4y) ]( k)
4. B=- 573 108 [7.5 106t-5 10-3(3x+4y) ](5 k)

A plane electromagnetic wave of frequency 20 MHz travels in free space along the +x direction. At a particular point in space and time, the electric field vector of the wave is Ey=9.3 V m-1. Then, the magnetic field vector of the wave at that point is

1. Bz=1.55 10-8 T
2. Bz=6.2 10-8 T
3. Bz=3.1 10-8 T
4. Bz=9.3 10-8 T

A time varying potential difference is applied between the plates of a parallel plate capacitor of capacitance 2.5 . The dielectric constant of the medium between the capacitor plates is 1 . It produces an instantaneous displacement current of 0.25 mA in the intervening space between the capacitor plates, the magnitude of the rate of change of the potential difference will be V s-1.

A parallel plate capacitor of area A=16 cm2 and separation between the plates 10 cm , is charged by a DC current. Consider a hypothetical plane surface of area A0=3.2 cm2 inside the capacitor and parallel to the plates. At an instant, the current through the circuit is 6A. At the same instant the displacement current through A0 is mA .