Electromagnetism MCQs

Question 1

A transmission line of characteristic impedance Zo = 50 ohms, phase velocity v = 2 x 108m15, and length I = 1 m is terminated by a load 11(30 - j 40) ohms. The input impedance of the line for a frequency of 100 MHz will be

Accepted Answer

(30 - 40) ohms

Answer

(30 + j40) ohms

Answer

(50 + j40) ohms

Answer

(50 - j40) ohms

Question 2

For incidence from dielectric medium (ci) into dielectric medium 2 (r.,2) the Brewster angle Op and the corresponding angle of tranmissionfor E2/e1 = 3 will be respectively

Accepted Answer

600 and 300

Answer

300 and 300

Answer

300 and 600

Answer

600 and 60?

Question 3

The Fleming's left hand rule correlates to

Accepted Answer

current, magnetic field and direction of force on a conductor

Answer

current, induced e.m.f and direction of force on a conductor

Answer

magnetic field, electric field and direction of force on a conductor

Answer

self induction, mutual induction and direction of force on a conductor

Question 4

Materials subjected to rapid reversal magnetism should have

Accepted Answer

high permeability and low hysteresis

Answer

large area of B-H loop

Answer

high co-ercivity and high retentivity loss

Answer

high co-ercivity and low density

Question 5

The main constituent of perm-alloy is

Accepted Answer

nickel

Answer

cobalt

Answer

chromium

Answer

tungsten

Question 6

The use of permanent magnets is not made in

Accepted Answer

anteena

Answer

magnetoys

Answer

transformers

Answer

material

Question 7

Paramagnetic permeability

Accepted Answer

slightly more than unity

Answer

slightly less than unity

Answer

equal to unity

Answer

equal to that ferromagnetic materials

Question 8

Two infinitely long parallel conductors in vacuum and separated 1 metre between centres when a current of materials have relative of 100 produce on each other a force of

Accepted Answer

2 x 10-7 N/m

Answer

2 x 10-2 N/m

Answer

2 x 10-3 N/m

Answer

2 x 10-5 N/m

Question 9

How much will be flux density in tesla units for flux of 45 p.Wb through 6 x 10-4m2,?

Accepted Answer

0.075 T

Answer

0.75 T

Answer

0.65 T

Answer

1.5 T