Electromagnetism MCQs

Question 1

The effective electrical length of an antenna is

Accepted Answer

greater than its physical length

Answer

equal to its physical length

Answer

half its physical length

Answer

1/X times its physical length

Question 2

Grounded antenna is used for frequencies of

Accepted Answer

upto about 1.6 MHz

Answer

1.0 MHz to 3 MHz

Answer

3 MHz to 30 MHz

Answer

above 30 MI-lz

Question 3

Parabolic antenna is used at

Accepted Answer

microwaves

Answer

long waves

Answer

medium waves

Answer

short waves

Question 4

EM waves in the frequency range 300 MHz to 30 GHz can be best transmitted using

Accepted Answer

Duct propagation

Answer

Groundwave propagation

Answer

sky wave propagation

Answer

none of these

Question 5

Skip distance is

Accepted Answer

metres 3 x 108

Answer

the minimum distance from the transmitter at which a stay wave of a given frequency is returned to earth from the ionosphere

Answer

the maximum distance from the transmitter at which a sky wave of a given frequency is returned to earth from the ionosphere3 x 108

Answer

)" ' metres

Question 6

For a plane good conductor, skin depth varies

Accepted Answer

directly as fj

Answer

directly as the conductiarty cr

Answer

inversely as a

Answer

inversely as /(7-

Question 7

For a good conductor, the depth of penetration of EM waves equals1

Accepted Answer

Ihrf24.2a

Answer

7.Fria"

Answer

1.17-70*

Question 8

Frequencies in the UHF range propagate by means of

Accepted Answer

space wave

Answer

sky waves

Answer

surface waves

Answer

ionospheric scatter

Question 9

In faraday rotation, the polarization phenomenon

Accepted Answer

is noreciprocal

Answer

does not exist

Answer

exists along the perpendicular direction

Answer

exists along the axis of the array