Q.1
An electromagnetic wave going through vaccum is described by E=o E sin(kx- ω t).Which of the following is independent of the wavelength?
  • a) ω
  • b)k/ ω
  • c) k ω
  • d)k
Q.2
Which of the following have zero average value in a plane electromagnetic wave?
  • a) Electric energy
  • b) Magnetic energy
  • c) Electric field
  • d)None of these.
Q.3
If the relative permeability and dielectric constant of a given medium are equal to µr and K respectively, then the refractive index of the medium is equalto__________
  • a) √(µr) K
  • b) √(µr) Eo
  • c) √(µo) Eo
  • d) √(µr)/ K
Q.4
Astraonomers have found that electromagnetic waves of wavelength 21cm arecontinuously reaching the Earth’s surface . Calculate the frequency of this radiation.(c=3 ×108m/s)
  • a)14.28 GHz
  • b)1.428 kHz
  • c)1.428 MHz
  • d)1.428 GHz
Q.5
Electric field in an electromagnetic wave is given by E=50 sinω(t-x/c) NC-1 .Intensity of this wave is ___________ Wm-2
  • a) 50
  • b)1.1×108
  • c)3.3
  • d)5.5×10-19
Q.6
The amplitude of the electric field in a parallel beam of light of intensity 2.0Wm-2is _______
  • a) 38.8NC-1
  • b) 19.4NC-1
  • c)9.7NC-1
  • d)None of these.
Q.7
Speed of electromagnetic wave is the same
  • a) for all wavelengths
  • b) in all media
  • c) for all intensities
  • d) for all frequencies
Q.8
The maximum electric field in a plane electromagnetic wave is 900NC-1 . The waveis going in the x direction and the electric field is in the y direction. The maximummagnetic field in the wave is ____________T
  • a)3×10-8
  • b) 3×10-6
  • c)27×10-6
  • d)27×1010
Q.9
Electromagnetic waves are produced by
  • a)a static charge
  • b)a moving charge
  • c)an accelerating charge
  • d)chargeless particles
Q.10
Maxwells equations are derived from the laws of___________
  • a)electricity
  • b) magnetism
  • c)both electricity and magnetism
  • d)mechanics
Q.11
Which of the following electromagnetic waves has the longest wavelength?
  • a) Radio waves
  • b) Infrared radiations
  • c) x rays
  • d) visible rays
Q.12
Which of the following electromagnetic waves has the highest frequency?
  • a)radio waves
  • b)micro waves
  • c) γ rays
  • d)x rays
Q.13
The maximum value of E in an electromagnetic waves in air is equal to 6.0×10-4 Vm . The maximum value of B is ____________
  • a) 1.8×105 T
  • b) 2×104 T
  • c)2×10-12 T
  • d)1.8×1013 T
Q.14
Dimensional formula of intensity of radiation is _____________
  • a) M1L2T-2
  • b) M1L0T-2
  • c)M1L1T-3
  • d)M1L0T-3
Q.15
The frequency of an electromagnetic wave in free space is 3MHz. When it passesthrough a medium of relative permeability εr=4.0 , then its frequency
  • a) becomes half
  • b) become doubled
  • c) remain same
  • d) become √2 times
Q.16
The frequency of electromagnetic wave having wavelength 25mm is _________ Hz
  • a)1.2 ×1010
  • b) 7.5 ×105
  • c)1.2 ×108
  • d)7.5 ×106
Q.17
Unit of energy density of electromagnetic wave is _________
  • a)Jm-3
  • b)Jm-2
  • c)wm-2
  • d)None of these
Q.18
What is the ratio of velocities of light rays of wavelengths 40000 Å and 80000 Å in vaccum ?
  • a)1:2
  • b) 1:1
  • c)2:1
  • d)cannot be determined
Q.19
Which of the following rays are not electromagnetic waves?
  • a) α rays
  • b) β rays
  • c) γ rays
  • d) heat rays
Q.20
A plane electromagnetic wave of frequency 25MHz travels in free space along thex direction. At a particular point in space and time E=6.3jVm-1 then Bat this point is__________
  • a)2.1 × 10-8 i T
  • b)2.1 × 10-8 k T
  • c)1.89× 109 k T
  • d)2.52× 10-7 k T
Q.21
The magnetic field in a plane electromagnetic wave is given By=2×10-7 sin ( 0.5×103x + 1.5×1011t) T
  • a) Ex=60 sin ( 0.5×103x + 1.5×1011t) V/m
  • b) Ez=60 sin ( 0.5×103x + 1.5×1011t) V/m
  • c) Ex=60 sin ( 1.5×103x + 0.5×1011t) V/m
  • d) Ex=60×1015 sin ( 1.5×103x + 0.5×1011t) V/m
Q.22
Light with an energy flux of w/m3 falls on a non-reflecting surface atnormal to surface. If the surface has an area of 20m2 . The average force exertedon the surface during 30 minutes is________
  • a)6.48×105 N
  • b)3.60×102 N
  • c)1.2×10-6 N
  • d)2.16×10-3N
Q.23
Energy density of an electromagnetic wave of intensity 0.02 Wm-2 is _______
  • a) 6.67×10-11 Jm-3
  • b)6×106 Jm-3
  • c)1.5×1010 Jm-3
  • d)none of the above
Q.24
The waves used in communication are generally called
  • a)γ ray
  • b) α ray
  • c) microwaves
  • d)radiowave
Q.25
For an electromagnetic wave, the phase difference between vectors E and B (faraway from the source)
  • a) 0
  • b) π /2
  • c) π
  • d) 3π/2
Q.26
The electric and magnetic field of an electromagnetic wave are
  • a) in phase and perpendicular to each other
  • b)in phase and parallel to each other
  • c) in opposite phase and perpendicular to each other
  • d) in opposite phase and parallel to each other
Q.27
Unit of µo C is same as that of
  • a)current
  • b)resistance
  • c) electric charge
  • d) velocity
Q.28
If the direction of magnetic field B at some instant is along +ve Z direction and the electromagnetic wave is propagating along +ve X direction, then the direction of electric field E at that instant is_________
  • a) along -ve Y direction
  • b) along +ve Y direction
  • c) along +ve X direction
  • d) along -ve X direction
Q.29
The velocity of light in vaccum can be changed by changing____
  • a) frequency
  • b)wavelength
  • c) amplitude
  • d) none of these
Q.30
Which of the Following is not a component of communication System ?
  • a) Transmitter
  • b) Transmission channel
  • c) Noise
  • d) Receiver
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