### Electronics and Communication Engineering - Electromagnetic Field Theory MCQs Part 2

1.A material has conductivity of 10-2 mho/m and a relative permittivity of 4. The frequency at which conduction current in the medium is equal to displacement current is

A. 45 MHz
B. 90 MHz
C. 450 MHz
D. 900 MHz

2.A transmission line is feeding 1 watt of power to a horn antenna having a gain of 10 dB. The antenna is matched to the transmission line. The total power radiated by the horn antenna into the free space is

A. 10 watt
B. 1 watt
C. 0.1 watt
D. 0.01 watt

3.An end fire array consisting of several half-wave lengths of directive gain 40, then find the width of major lobe

A. 60
B. 50
C. 51.25
D. None of the above

4.A uniform plane EM wave incident normally on a plane surface of a dielectric material is reflected with a VSWR of 3. What percentage of incident power that is reflected?

A. 10%
B. 25%
C. 50%
D. 75%

5.Poynting vector is associated with which of the following?

A. Power flow in electromagnetic
B. Flux in magnetic field
C. Charge in electrostatic field
D. Current in electrostatic field

6.A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 cm. And if each array element feeding with 1 amp. current and operating at same frequency then find the radiated power

A. 730 W
B. 73 W
C. 100 W
D. None

7.For static magnetic field Maxwell's curl equation is given by

A. ∇ . = μ0
B. ∇ x = 0
C. ∇ x = μ0
D. ∇ x = μ0/

8.If wave of critical frequency 30 MHz is departing at an angle of 60°, then the MUF is given to be

A. 10 MHz
B. 15 MHz
C. 30 MHz
D. 60 MHz

9.An antenna having an effective temperature of 27°K is fed into a microwave amplifier that has an effective noise temperature of 30 K. Calculate the available noise power per unit bandwidth

A. 30 K
B. 57 K
C. 27 K
D. 3K, K is Boltzmann constant

10.Two identical and parallel dipole antenna are kept apart by a distance of λ/4 in the H-plane. They are fed with equal currents but the right most antenna has a phase shift of + 90°. The radiation pattern is given as

A.
B.
C.
D.