# 600+ Electromagnetics Solved MCQs

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56.5k
101.

## The volume of a parallelepiped in Cartesian is

A. dv = dx dy dz
B. dv = dx dy
C. dv = dy dz
D. dv = dx dz
Answer» A. dv = dx dy dz
102.

A. true
B. false
103.

## The spherical equivalent of the vector B = yi + (x + z)j located at (-2,6,3) is given by

A. (7,64.62,71.57)
B. (7,-64.62,-71.57)
C. (7,-64.62,71.57)
D. (7,64.62,-71.57)
104.

A. distance
B. intensity
C. magnitude
D. geometry
105.

## The cylindrical coordinate system is also referred to as

A. cartesian system
B. circular system
C. spherical system
D. space system
106.

## Transform the vector B=yi+(x+z)j located at point (-2,6,3) into cylindrical coordinates.

A. (6.325,-71.57,3)
B. (6.325,71.57,3)
C. (6.325,73.57,3)
D. (6.325,-73.57,3)
107.

A. 1, ρ ,1
B. 1, 1, 1
C. 0,1,0
D. 1,0,0
108.

## A charge located at point p (5,30⁰,2) is said to be in which coordinate system?

A. cartesian system
B. cylindrical system
C. spherical system
D. space system
109.

A. true
B. false
110.

## The pressure inside a piston cylinder is a variable of

B. plane angle
C. z plane distance
D. constant, not a variable
111.

## Charges filled inside a cylindrical will possess flux in which direction?

A. upwards
B. downwards
C. laterally outwards
D. inwards
112.

## Rectangular waveguides dominate the circular waveguides. Find the reason.

A. low cut-off frequency
B. easy to design
C. more wave propagation
D. the statement is false
113.

## Convert the point (3,4,5) from Cartesian to spherical coordinates

A. (7.07,45⁰,53⁰)
B. (0.707,45⁰,53⁰)
C. (7.07,54⁰,63⁰)
D. (0.707,54⁰,63⁰)
114.

## Example of spherical system in the following is

A. charge in space
B. charge in box
C. charge in dielectric
D. uncharged system
115.

A. true
B. false
116.

## Choose which of following condition is not required for a waveguide to exist.

A. the dimensions should be in accordance with desired frequency
B. cut-off frequency should be minimum 6ghz
C. the shape should be spherical
D. no specific condition is required for waveguide design
Answer» C. the shape should be spherical
117.

## Find the spherical coordinates of A(2,3,-1)

A. (3.74, 105.5⁰, 56.13⁰)
B. (3.74, 105.5⁰, 56.31⁰)
C. (3.74, 106.5⁰, 56.13⁰)
D. (3.74, 106.5⁰, 56.31⁰)
118.

## Find the Cartesian coordinates of B(4,25⁰,120⁰)

A. (0.845, 1.462, 3.625)
B. (-0.845, 1.462, 3.625)
C. (-8.45, 2.462, 6.325)
D. (8.45, 2.462, 6.325)
119.

A. true
B. false
120.

A. -2i + j
B. 2i + k
C. i + 2j
D. –i – 2k
121.

## The scalar factor of spherical coordinates is

A. 1, r, r sin θ
B. 1, r, r
C. r, r, 1
D. r, 1, r
Answer» A. 1, r, r sin θ
122.

## The permittivity is also called

A. electrostatic energy
B. dielectric constant
C. dipole moment
D. susceptibility
123.

## Dielectric constant will be high in

A. conductors
B. semiconductors
C. insulators
D. superconductors
124.

## Insulators perform which of the following functions?

A. conduction
B. convection
C. provide electrical insulation
D. allows current leakage at interfaces
125.

A. 1.26
B. 3.26
C. 5.1
D. 1
126.

A. 1
B. 0
C. 2
D.
127.

A. e = p
B. d = p
C. b = p
D. h = p
128.

A. ceramics
B. plastics
C. mercury
D. rubber
129.

A. >6 ev
B. 0.2-0.4 ev
C. 0.4-2 ev
D. 2-6 ev
130.

## Conduction in metals is due to

A. electrons only
B. electrons and holes
C. holes only
D. applied electric field
131.

A. 1ev
B. 2ev
C. 3ev
D. 4ev
132.

A. peak value
B. average value
C. rms value
D. zero
133.

## The current in a metal at any frequency is due to

A. conduction current
B. displacement current
C. both conduction and displacement current
D. neither conduction nor displacement current
134.

## For conductors, the free electrons will exist at

A. valence band
B. middle of valence and conduction band
C. will not exist
D. conduction band
135.

## The current flowing through an insulating medium is called

A. conduction
B. convection
D. susceptibility
136.

A. iron
B. ceramics
C. plastic
D. magnesium
137.

A. compression
B. heating
C. doping
D. freezing
138.

A. 3
B. 5
C. 8
D. 16
139.

## For a dielectric which of the following properties hold good?

A. they are superconductors at high temperatures
B. they are superconductors at low temperatures
C. they can never become a superconductor
D. they have very less dielectric breakdown voltage
Answer» B. they are superconductors at low temperatures
140.

## he magnetic field which destroys the superconductivity is called

A. diamagnetic field
B. ferromagnetic field
C. ferrimagnetic field
D. critical field
141.

A. positive
B. negative
C. zero
D. infinity
142.

## The superconducting materials will be independent of which of the following?

A. magnetic field
B. electric field
C. magnetization
D. temperature
143.

A. 9
B. 36
C. 0.11
D. 4.5
144.

## The best definition of polarisation is

A. orientation of dipoles in random direction
B. electric dipole moment per unit volume
C. orientation of dipole moments
D. change in polarity of every dipole
Answer» B. electric dipole moment per unit volume
145.

## Polarizability is defined as the

A. product of dipole moment and electric field
B. ratio of dipole moment to electric field
C. ratio of electric field to dipole moment
D. product of dielectric constant and dipole moment
Answer» B. ratio of dipole moment to electric field
146.

A. electronic
B. ionic
C. orientational
D. interfacial
147.

## The total polarisation of a material is the

A. product of all types of polarisation
B. sum of all types of polarisation
C. orientation directions of the dipoles
D. total dipole moments in the material
Answer» B. sum of all types of polarisation
148.

## In the given types of polarisation, which type exists in the semiconductor?

A. electronic
B. ionic
C. orientational
D. interfacial or space charge
Answer» D. interfacial or space charge
149.

A. ionic
B. orientational
C. interfacial
D. electronic
150.

A. diamond
B. sulphur
C. silicon
D. germanium
151.

A. 2562
B. 16
C. 256
D. 64
152.

## Curie-Weiss law is applicable to which of the following materials?

A. piezoelectric
B. ferroelectric
C. pyroelectric
D. anti-ferroelectric
153.

## Curie-Weiss law is used to calculate which one of the following?

A. permittivity
B. permeability
C. electric susceptibility
D. magnetic susceptibility
154.

A. (2/3)
B. (3/2)
C. (-3/2)
D. (-2/3)
155.

## When a dielectric loses its dielectric property, the phenomenon is called

A. dielectric loss
B. dielectric breakdown
C. polarisation
D. magnetization
156.

## Choose the best definition of dielectric loss.

A. absorption of electric energy by dielectric in an ac field
B. dissipation of electric energy by dielectric in a static field
C. dissipation of heat by dielectric
D. product of loss tangent and relative permittivity
Answer» A. absorption of electric energy by dielectric in an ac field
157.

A. 1
B. -1
C. 0
D.
158.

## For a conservative field which of the following equations holds good?

A. ∫ e.dl = 0
B. ∫ h.dl = 0
C. ∫ b.dl = 0
D. ∫ d.dl = 0
Answer» A. ∫ e.dl = 0
159.

A. 12π
B. 24π
C. 36π
D. 48π
160.

A. 12
B. 24
C. 48
D. 96
161.

A. e
B. d
C. h
D. b
162.

A. 1.41
B. 3.5
C. 2.2
D. 1.73
163.

## In free space, the Poisson equation becomes

A. maxwell equation
B. ampere equation
C. laplace equation
164.

## If Laplace equation satisfies, then which of the following statements will be true?

A. potential will be zero
B. current will be infinite
C. resistance will be infinite
D. voltage will be same
Answer» B. current will be infinite
165.

## Suppose the potential function is a step function. The equation that gets satisfied is

A. laplace equation
B. poisson equation
C. maxwell equation
D. ampere equation
166.

A. true
B. false
167.

## Poisson equation can be derived from which of the following equations?

A. point form of gauss law
B. integral form of gauss law
C. point form of ampere law
D. integral form of ampere law
Answer» A. point form of gauss law
168.

A. 19
B. -5
C. 5
D. -19
169.

## Find the electric field of a potential function given by 20 log x + y at the point (1,1,0).

A. -20 i – j
B. -i -20 j
C. i + j
D. (i + j)/20
Answer» A. -20 i – j
170.

A.
B. -∞
C. unity
D. zero
171.

A. qv
B. 1⁄2qv
C. 2qv
D. qv2
172.

A. 100j
B. 200j
C. 300j
D. 400j
173.

## When do we get maximum energy from a set of capacitors?

A. when they are connected in parallel
B. when they are connected in series
C. both in series and parallel
D. insufficient information provided
Answer» A. when they are connected in parallel
174.

A. 8.6kj
B. 64kj
C. 64j
D. 6.4kj
175.

A. 128kj
B. 1.28kj
C. 12.8kj
D. 1280j
176.

A. 192kj
B. 1.92kj
C. 19.2kj
D. 1920j
177.

A. v/m2
B. mv/m2
C. mv/m
D. vm
178.

## If the Voltage increases, what happens to dielectric strength?

A. increases
B. decreases
C. remains the same
D. becomes zero
179.

## If the thickness of the material increases, what happens to the dielectric strength?

A. increases
B. decreases
C. remains the same
D. becomes zero
180.

A. water
B. mica
C. air
D. glass
181.

A. transistors
B. resistors
C. inductors
D. dc motors
182.

A. infinity
B. zero
C. 100a
D. 1000a
183.

## The flow of electrons in dielectric is due to

A. conduction
B. potential difference
C. breakdown
D. resistance
184.

## The flow of electrons which does not pass through the battery is known as

A. displacement current
B. leakage current
C. either displacement or leakage current
D. neither displacement nor leakage current
185.

## The free electrons in practical dielectrics is due to _

A. there are no free electrons
B. conductors
C. impurities
D. both conductors and impurities
186.

## What is the type of current where the electrons actually move?

A. displacement current
B. conduction current
C. both conduction and displacement current
D. neither conduction nor displacement current
187.

## What is the type of current caused due to variations in the field?

A. displacement current
B. conduction current
C. both conduction and displacement current
D. neither conduction nor displacement current
188.

## Under normal conditions capacitors have _

A. displacement current
B. conduction current
C. both conduction and displacement current
D. neither conduction nor displacement current
189.

## Under normal conditions capacitors have _

A. displacement current
B. conduction current
C. both conduction and displacement current
D. neither conduction nor displacement current
190.

## What is the unit for displacement current?

A. no unit
B. ampere
C. coulomb
D. ampere/coulomb
191.

## Displacement current depends on _

A. moving charges
B. change in time
C. both moving charges and change in time
D. neither moving charges nor change in time
192.

## Magnetic fields between the parallel plates of a capacitor are due to?

A. displacement current
B. conduction current
C. both conduction and displacement current
D. neither conduction nor displacement current
193.

## The free electrons in practical dielectrics are due to

A. there are no free electrons
B. conductors
C. impurities
D. displacement currents
194.

## Paper capacitor is a type of _

A. fixed capacitor
B. variable capacitor
C. either fixed or variable depending on its usage
D. neither fixed nor variable
195.

## A capacitor using chemical reactions to store charge is _

A. paper capacitor
B. ceramic capacitor
C. polyester capacitor
D. electrolyte capacitor
196.

## Which, among the following, is the odd one out?

A. ceramic capacitor
B. electrolyte capacitor
C. tuning capacitor
D. paper capacitor
197.

## In a variable capacitor, capacitance can be varied by

A. turning the rotatable plates in or out
B. sliding the rotatable plates
C. changing the plates
D. changing the material of plates
Answer» A. turning the rotatable plates in or out
198.

## The simplest kind of capacitor is _

A. ceramic capacitor
B. electrolyte capacitor
C. tuning capacitor
D. paper capacitor
199.

## Capacitor preferred when there is high frequency in the circuits is _

A. electrolyte capacitor
B. mica capacitor
C. air capacitor
D. glass capacitor
200.

## The type of capacitors used in communication transmitters are?

A. electrolyte capacitor
B. variable capacitor
C. air capacitor
D. glass capacitor