Electromagnetism MCQs

Question 1

When a particular mode is excited in a waveguide, there appears an extra electric component, in the direction of propagation. The resulting mode is

Accepted Answer

transverse-magnetic

Answer

transverse-electric

Answer

longitudinal

Answer

transverse-electromagnetic

Question 2

As aresult of reflections from a plane conducting wall, electromagnetic waves acquire an apparent velocity greater than the velocity of light in space. This is called the

Accepted Answer

phase velocity

Answer

velocity of propagation

Answer

normal velocity

Answer

group velocity

Question 3

A(75 ? j50)12 load is connected to a coaxial transmission line of Zo = 7512, at 10 GHz. The best method of matching consists in connecting

Accepted Answer

an inductance at the load

Answer

a short-circuited stub at the load

Answer

a capacitance at some specific distance from the load

Answer

a short-circuited stub at some specific distance from the load

Question 4

The velocity factor of a transmission line

Accepted Answer

depends on the dielectric constant of the material used

Answer

increases the velocity along the transmission line

Answer

is governed by the skin effect

Answer

is higher for a solid dielectric than for air.

Question 5

Short-circuited stubs are preferred to open-circuited stubs because the latter are

Accepted Answer

made of a transmission line with a different characteristic impedance

Answer

more difficult to make and connect

Answer

liable to radiate

Answer

incapable of giving a reactances.

Question 6

Waveguides are used microwave signals because

Accepted Answer

the would be too bulky at lower frequencies.

Answer

they depend on propagation which microwaves only

Answer

losses would be too heavy at lower frequencies

Answer

there are no generators powerful enough to excite them at lowe frequencies

Question 7

Which of the following equations represents the Gauss' law in a homogeneous isotropic medium.

Accepted Answer

D . ds = JJJ pdV

Answer

VxH=D

Answer

V.J+p=0

Answer

V. E = p/c

Question 8

A transmission line whose characteristic impedance is a pure resistance

Accepted Answer

may not be a lossless line

Answer

must be a lossless line

Answer

must be a distortionless line

Answer

may not be a distortion less line.

Question 9

Consider a transmission line of characterisitc impedance 50 ohm. Let it be terminated at one end by + j50 ohm. The VSWR produced by it in the tramission line will be

Accepted Answer

+j

Answer

1

Answer

0