Multiple Choice Questions on Electric Fields and Magnetic Fields - 1

Important Multiple Choice Questions From Electrical and Magnetic Fields

1.       Transmission of power to a load over transmission line achieves optimum value when standing-wave ration (SWR) becomes

A)     2:1

B)      1:2

C)      1:1

D)     1:4

2.       White noise is that signal whose frequency spectrum

A)     Extends over infinite range

B)      Has flat spectral density

C)      Has spectral density varying as 1/f

D)     Has limited number of frequency components

3.       The depth of penetration of wave in a lossy dielectric increases with increasing

A)     Conductivity

B)      Permeability

C)      Wavelength

D)     Permittivity

4.       The intrinsic impedance of copper at high frequencies is

A)     Purely resistive

B)      Purely inductive

C)      Complex with a capacitive component

D)     Complex with an inductive component

5.       When electromagnetic waves are propagated in a wave guide

A)     They travel along the border walls of the guide

B)      They are reflected from the walls but do not travel along them

C)      They travel through the dielectric without touching the walls

D)     They travel along all four walls of the wave guide

6.       As a result 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

A)     Velocity of propagation

B)      Normal velocity

C)      Group velocity

D)     Phase velocity

7.       According to lenz’s law, the direction of induced emf and hence current

A)     May be found by the right-hand rule

B)      Is always determined by the rate of cutting flux

C)      Always opposes the cause producing it

D)     Depends on whether the coil is wound with a right or left-hand spiral

8.       Two infinite parallel metal plates are charged with equal surface charge density of the same polarity. The electric field in the gap between the plates is

A)     The same as that produced by one plate

B)      Double of the field produced by one plate

C)      Dependent on coordinates of field point

D)     Zero

9.       Inside a hallow conducting sphere

A)     Electric field is zero

B)      Electric field is a non zero constant

C)      Electric field changes with the magnitude of the charge given to the conductor

D)     Electric field changes with distance from the centre of the sphere

10.   Copper behaves as a

A)     Conductor always

B)      Conductor or dielectric depending on the applied electric field strength

C)      Conductor or dielectric depending on the frequency

D)     Conductor or dielectric depending on the electric current density