Electromagnetic Field Theory MCQs

Practice and Learn through MCQs and Quizzes. W3Definitions.com have 266 Electromagnetic Field Theory MCQs

__________ acts as a depolarizer in a dry cell.

  • A. ammonium chloride
  • B. carbon powder
  • C. manganese dioxide
  • D. zinc chloride
  • Correct Answer: Option C

__________ will have the least value of relative permeability.

  • A. Palladium
  • B. Silver
  • C. Cobalt
  • D. Iron
  • Correct Answer: Option B

∇2 is

  • A. vector
  • B. scalar
  • C. depend on direction
  • D. none
  • Correct Answer: Option B

1 dB is equal to __________ nepier

  • A. 8.6
  • B. 6.8
  • C. 8
  • Correct Answer: Option A

A (75 – j 40) W load is connected to a co-axial line of z0 = 75ω at 6 MHz. The load matching on the line can be accomplished by connecting

  • A. a short circuit stub at the load
  • B. an inductance at the load
  • C. a short circuit stub at a specific distance from the load
  • D. a capacitance at a specific distance from the load
  • Correct Answer: Option B

A conductor is said to be perfect if it has __________ conductivity

  • A. finite
  • B. infinite
  • C. unity
  • D. zero
  • Correct Answer: Option B

A dominant wave is characterised by which of the following?

  • A. No attenuation
  • B. Lowest cut off wavelength
  • C. Highest cut off wavelength
  • D. All of the above
  • Correct Answer: Option C

A higher directivity is specified by

  • A. high gain low BW (Beamwidth)
  • B. high gain high BW
  • C. low gain high BW
  • D. none of the above
  • Correct Answer: Option A

A loss less transmission line is terminated in a load which reflects a part of the incident power. The measured VSWR is 2. The percentage of the power that is reflected back is

  • A. 57.73
  • B. 33.33
  • C. 0.11
  • D. 11.11
  • Correct Answer: Option D

A medium is said to be isotropic when

  • A. ∈ = 0
  • B. ∈ = μ
  • C. ∈ = σ
  • D. ∈ is scalar constant
  • Correct Answer: Option D

A parabolic antenna produces a radiation pattern which is

  • A. circularly polarized
  • B. highly directional
  • C. omnidirectional
  • D. linearly polarized
  • Correct Answer: Option B

A plane EM wave is travelling in an unbound loss less dielectric having μy = 1 and εy = 4, the time average Poynting vector of the wave is 5 W/m3 . The phase velocity vp (assuming velocity of light as 3 x 108 m/sec) is

  • A. 1.5 x 108 m/sec
  • B. 3 x 108 m/sec
  • C. 2.5 x 108 m/sec
  • D. 0.5 x 108 m/sec
  • Correct Answer: Option A

A rectangular waveguide (2.29 x 1.02) cm operates at a freq. of 11 GHz in TE10 mode. If the maximum potential gradient of the signal is 5 kV/cm, then the maximum power handling capacity of the waveguide will be

  • A. 31.11 mW
  • B. 31.11 W
  • C. 31.11 kW
  • D. 31.11 MW
  • Correct Answer: Option C

A rectangular waveguide is a

  • A. rectangular conducting wire to propagate electromagnetic waves
  • B. hollow rectangular walled room carrying electromagnetic wave
  • C. hollow rectangular conducting tube through which electromagnetic waves can be propagated
  • D. tube antenna to transmit and receive electromagnetic waves
  • Correct Answer: Option C

A square corner reflector is used in

  • A. radio astronomy
  • B. tv broadcast
  • C. point to point communication
  • D. all of the above
  • Correct Answer: Option D

A square corner reflector is used in which of the following?

  • A. TV broadcast
  • B. Point-to-point communication
  • C. Radio astronomy
  • D. All of the above
  • Correct Answer: Option D

A TEM wave incident obliquely on a dielectric boundary with εr1 = 2 and εr2 = 1, the angle of incidence for total reflection is

  • A. 30°
  • B. 60°
  • C. 45°
  • D. 90°
  • Correct Answer: Option C

A time varying magnetic field produces

  • A. electric field only
  • B. magnetic field only
  • C. both magnetic and electric fields
  • D. none of the above
  • Correct Answer: Option C

A transmission line has characteristics impedance of (75 + j 0.01) Ω and is terminated in a load impedance of (70 + j 50) Ω. The reflection coefficient will be

  • A. 0.08 + j 0.32
  • B. 0.32 + j 1.38
  • C. 0.70 - j 2.97
  • D. 1.1 + j 0.32
  • Correct Answer: Option A

A transmission line has primary constants R, L, G and C and secondary constant z0 and γ = (a + Jβ). If the line is loss less, then

  • A. R = 0, G ≠ 0, and a = 0
  • B. R = 0, G = , 0 and β = |r|
  • C. G = 0, = β
  • D. R = 0, G = 0, = 0, β = |r|
  • Correct Answer: Option A

A uniform wave have components

  • A. in the perpendicular direction E existing while H is zero
  • B. in the direction of propagation E existing while H is zero
  • C. E and H are zero in direction perpendicular to direction of propagation
  • D. E and H existing only in direction perpendicular to direction of propagation
  • Correct Answer: Option D

A very reliable service has to be established between two points on earth separated by 1000 km. The band that will be used as

  • A. MF
  • B. VHF
  • C. VLF
  • D. HF
  • Correct Answer: Option C

A waveguide behave as

  • A. high Pass filter
  • B. low Pass filter
  • C. band Pass filter
  • D. all Pass filter
  • Correct Answer: Option A

A waveguide operated below cut off frequency can be used as

  • A. phase shifter
  • B. an attenuator
  • C. an isolator
  • D. none
  • Correct Answer: Option B

A λ/8 section of transmission line is determined of load impedance of (2 – j 5) Ω. If characteristic impedance of line is 10 Ω. Then input impedance of line is

  • A. 10 Ω
  • B. (6.9 + j 7.24) Ω
  • C. (1.75 + j 3.098) Ω
  • D. (2 - j 5) Ω
  • Correct Answer: Option C

Absolute permeability (μ) is given by __________ henry/metre

  • A. 4 x 10-12
  • B. 4 x 10-7
  • C. 8.854 x 10-12
  • D. 8.854 x 10-7
  • Correct Answer: Option B

After reflection from a plane conducting surface, the apparent velocity of electromagnetic wave becomes greater than the velocity of light in free space is called

  • A. conventional velocity
  • B. phase velocity
  • C. propagation velocity
  • D. group velocity
  • Correct Answer: Option B

Alternating current can induce voltage because it has magnetic field which is

  • A. constant
  • B. time varying
  • C. stronger field than D.C.
  • D. closed loop nature.
  • Correct Answer: Option B

An alternating current or voltage is that which

  • A. changes in magnitude only
  • B. changes in direction only
  • C. both (a) and (b)
  • D. has a random movement of electrons
  • Correct Answer: Option C

An antenna array pattern is to used for increasing

  • A. gain
  • B. directivity
  • C. directive gain
  • D. all
  • Correct Answer: Option D

An antenna having a high Q has

  • A. lower BW
  • B. higher BW
  • C. flat response
  • D. none of the above
  • Correct Answer: Option A

An electric charge Q is placed in a dielectric medium which of the following quantities are independent of the dielectric constant ε of the medium

  • A. electric potential V and electric field intensity E
  • B. displacement density D and displacement φ
  • C. electric field intensity E and displacement φ
  • D. electric potential V and displacement φ
  • Correct Answer: Option B

An electromagnetic wave incident on a perfect conductor is

  • A. fully transmitted
  • B. partially transmitted
  • C. entirely reflected
  • D. none of the above
  • Correct Answer: Option C

An electromagnetic wave incidents on a perfect insulator at an angle. If the wave is not entirely parallel polarized, then

  • A. the reflected wave will be entirely polarized parallel to the plane of incidence
  • B. there will be no reflection
  • C. the reflected wave will be entirely polarized perpendicular to the plane of incidence
  • D. any of the above
  • Correct Answer: Option C

An electron when placed midway between two equal and opposite charges will

  • A. remain stationary
  • B. oscillate between the charges
  • C. be thrown out of the field
  • D. spin in the field
  • Correct Answer: Option A

An end fire array consisting of several half-wave lengths of directive gain 40, then array length will be

  • A. 10 λ
  • B. 100 λ
  • C. 20 λ
  • D. 5 λ
  • Correct Answer: Option A

An open coil has

  • A. zero resistance and inductance
  • B. zero resistance and high inductance
  • C. infinite resistance and zero inductance
  • D. infinite resistance and normal inductance
  • Correct Answer: Option C

Analysis of EM wave in waveguide based on

  • A. circuit theory
  • B. field theory
  • C. optical theory
  • D. both (a) and (b)
  • Correct Answer: Option B

Antenna beamwidth is

  • A. measure of directivity
  • B. measure of angle
  • C. measure of radiation pattern
  • D. measure of power pattern
  • Correct Answer: Option A

Antenna is a __________ element

  • A. passive
  • B. active
  • C. resistive
  • D. capacitive
  • Correct Answer: Option A