Electromagnetic Field Theory

MCQsQuestion.com has 423 Question/Answers about Topic Electromagnetic Field Theory

When the phase velocity of an EM wave depends on frequency in any medium the phenomenon is called

When the phase velocity of an EM wave depends on frequency in any medium the phenomenon is called
  • A. scattering
  • B. polarisation
  • C. absorption
  • D. dispersion
  • Correct Answer: Option B

In case of surface waves the field strength at a point is directly proportional to

In case of surface waves the field strength at a point is directly proportional to
  • A. antenna height
  • B. wave frequency
  • C. current of the antenna
  • D. distance of the point from the antenna
  • Correct Answer: Option D

The ground waves eventually disappear as one moves away from the transmitter because of

The ground waves eventually disappear as one moves away from the transmitter because of
  • A. tilting
  • B. maximum single-hop distance limitation
  • C. interference from the sky waves
  • D. loss of line-of sight condition
  • Correct Answer: Option A

Which layer is least important in high frequency propagation?

Which layer is least important in high frequency propagation?
  • A. D layer
  • B. E layer
  • C. F1 layer
  • D. F2 layer
  • Correct Answer: Option A

For F1 layer the maximum ionic density is 2.3 x 104 electrons per cc. The critical frequency for this layer will be

For F1 layer the maximum ionic density is 2.3 x 104 electrons per cc. The critical frequency for this layer will be
  • A. 1.36 MHz
  • B. 13.6 MHz
  • C. 136 MHz
  • D. 1360 MHz
  • Correct Answer: Option B

A satellite that simply reflect back the signals from one region of the earth to the other region is known as

A satellite that simply reflect back the signals from one region of the earth to the other region is known as
  • A. orbiting satellite
  • B. geostationary satellite
  • C. active satellite
  • D. passive satellite
  • Correct Answer: Option D

Which type of fading causes serious distortion of modulated signal?

Which type of fading causes serious distortion of modulated signal?
  • A. Selective fading
  • B. Interference fading
  • C. Absorption fading
  • D. Polarization fading
  • Correct Answer: Option A

The fluctuation in the received signal strength at the receiver of a random variation in the received signal is known as

The fluctuation in the received signal strength at the receiver of a random variation in the received signal is known as
  • A. fluctuation
  • B. fading
  • C. absorption
  • D. cycling
  • Correct Answer: Option B

The duration of sunspot cycle is

The duration of sunspot cycle is
  • A. 1 year
  • B. 11 years
  • C. 55 years
  • D. 100 years
  • Correct Answer: Option B

Which of the following is multiband HF receiving antenna?

Which of the following is multiband HF receiving antenna?
  • A. Square loop
  • B. Log-periodic
  • C. Conical horn
  • D. Folded dipole
  • Correct Answer: Option B

Which of the following statement is incorrect?

Which of the following statement is incorrect?
  • A. Z0 is an ac characteristic that is the same for any length of time
  • B. The characteristic impedance can be measured approximately with a sensitive ohm meter
  • C. A line terminated in its Z0 is a flat or non-resonant line
  • D. A twin lead has higher Z0 but lower losses than coaxial cable
  • Correct Answer: Option B

Which of the following is not a wideband antenna?

Which of the following is not a wideband antenna?
  • A. Marconi
  • B. Discone
  • C. Helical
  • D. Folded dipole
  • Correct Answer: Option A

The skip distance does not depends upon

The skip distance does not depends upon
  • A. the power transmitted
  • B. type of wave propagation
  • C. angle of beaming of the wave
  • D. frequency of the signal transmitted
  • Correct Answer: Option B

The M.K.S. unit of magnetic field intensity is

The M.K.S. unit of magnetic field intensity is
  • A. ampere
  • B. ampere/metre
  • C. volt
  • D. volt/metre
  • Correct Answer: Option B

The velocity factor of a transmission line

The velocity factor of a transmission line
  • A. mainly depends on the skin effect
  • B. is always higher for a solid dielectric than for air
  • C. mainly depends on the dielectric constant of the material used
  • D. increases the velocity along the transmission line
  • Correct Answer: Option C
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