Electromagnetic Waves  MCQs

MCQs of Electromagnetic Waves

Showing 51 to 60 out of 112 Questions
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51.
The maximum value of E→ in an electromagnetic wave is equal to 18 Vm-1 . Thus the maximum value of B→ is ____ .
(a) 3 × 10-6 T
(b) 6 × 10-8 T
(c) 9 × 10-9 T
(d) 2 × 10-10 T
Answer:

Option (b)

52.
An electromagnetic wave passing through the space is given by the equations : E = E0 sin (ωt - kx) and B = B0 sin (ωt - kx).  Which of the following is true ?
(a) E0B0 = ωk
(b) E0ω = B0k
(c) E0k = B0ω
(d) E0B0 = 1ωk
Answer:

Option (c)

53.
The frequency of an electromagnetic wave in free space is 2 MHz. When it passes through a region of relative permittivity εr = 4.0, then its wavelength _____ and frequency _____ .
(a) becomes double, becomes half
(b) becomes double, remains constant
(c) becomes half, becomes double
(d) becomes half, remains constant
Answer:

Option (d)

54.
The r.m.s. value of electric field of the radiation coming from the sun is 720 N/C. The average radiation density is _____ Jm-3 .
(a) 81.35 × 10-12
(b) 3.3 × 10-3
(c) 4.58 × 10-6
(d) 6.37 × 10-9
Answer:

Option (c)

55.
At large distance from the source, E→ and B→ are in phase and the decrease in their magnitude is comparatively slower with distance r as per _____, and these components are called _____ components.
(a) r-3, inductive
(b) r-1, radiated
(c) r-3, radiated
(d) r-1, inductive
Answer:

Option (b)

56.
At room temperature, if the relative permittivity of water be 80, and the relative permeability be 0.0222, then the velocity of light in water is _____ ms-1.
(a) 3 × 108
(b) 2.5 × 108
(c) 2.25 × 108
(d) 3.5 × 108
Answer:

Option (c)

57.
If the electric field associated with a radiation of frequency 10 MHz is E = 10 sin (kx - ωt) mvm, then its energy density is _____ jm-3.(ε0 = 8.85 × 10-12C2N-1m-2)
(a) 4.425 × 10-16
(b) 6.26 × 10-14
(c) 8.85 × 10-16
(d) 8.85 × 10-14
Answer:

Option (a)

58.
The intensity of a plane electromagnetic wave with B0 = 1.0 × 10-4 T is _____ Wm-2. (c = 3 × 108ms-1, μ0 = 4π × 10-7NA-2)
(a) 2.38 × 106
(b) 1.19 × 106
(c) 6 × 105
(d) 4.76 × 106
Answer:

Option (b)

59.
Displacement current is measured in _____ .
(a) Ampere
(b) Coulomb
(c) C - m
(d) As-1
Answer:

Option (a)

60.
The displacement current exists whenever the following quantity changes with time.
(a) electric field
(b) charge
(c) magnetic flux
(d) dielectric constant
Answer:

Option (a)

Showing 51 to 60 out of 112 Questions
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