Electromagnetic Waves

Average force exerted on a non-reflecting surface at normal incidence is 2.4 10-4 N. If 360 W/cm2 is the light energy flux during span of 1 hour 30 minutes, then the area of the surface is:

1. 20 m2
2. 0.2 m2
3. 0.1 m2
4. 0.02 m2

Electromagnetic waves travel in a medium with speed of 1.5 108 m s-1. The relative permeability of the medium is 2.0. The relative permittivity will be:

1. 4
2. 1
3. 2
4. 5

In the given electromagnetic wave Ey = 600 ( t - kx) Vm-1, intensity of the associated light beam is (in W/m2) : (Given 0 = 9 10-12 C2 N-1 m-2)

1. 486
2. 729
3. 243
4. 972

An alternating voltage of amplitude 40 V and frequency 4 kHz is applied directly across the capacitor of 12 . The maximum displacement current between the plates of the capacitor is nearly :

1. 10 A
2. 8 A
3. 13 A
4. 12 A

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

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

The electric field in an electromagnetic wave is given by E= i40 (t-z/c) NC-1. The magnetic field induction of this wave is (in SI unit) :

1. B= j 40c (t-z/c)
2. B= i 40c (t-z/c)
3. B= j40 (t-z/c)
4. B= k 40c (t-z/c)

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

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

A parallel plate capacitor has a capacitance C=200 pF. It is connected to 230 V ac supply with an angular frequency 300 rad/s. The rms value of conduction current in the circuit and displacement current in the capacitor respectively are :

1. 14.3 and 143
2. 13.8 and 13.8
3. 13.8 and 138
4. 1.38 and 1.38

If frequency of electromagnetic wave is 60 MHz and it travels in air along z direction then the corresponding electric and magnetic field vectors will be mutually perpendicular to each other and the wavelength of the wave (in m) is :

1. 2.5
2. 5
3. 10
4. 2

In a plane EM wave, the electric field oscillates sinusoidally at a frequency of 5 1010 Hz and an amplitude of 50 Vm-1. The total average energy density of the electromagnetic field of the wave is : [Use 0=8.85 10-12 C2/Nm2 ]

1. 4.425 10-8 Jm-3
2. 2.212 10-10 Jm-3
3. 2.212 10-8 Jm-3
4. 1.106 10-8 Jm-3