Electrical Engineering Viva Questions

MCQs | Single Phase Motors | Electrical Machine Questions

MCQs | Single Phase Motors | Electrical Machine Questions


MCQ types Questions and Answers of single phase motor are provided below which is more important to grow knowledge about electrical machine Questions and for GATE examination also.

MCQs | Single Phase Motors | Electrical Machine Questions

Questions and Answers ( single phase motors)


Q.1

Which of the following single phase motors has relatively poor starting torque?

(a) universal Motor

(b) repulsion Motor

(c) capacitor Motor

(d) all single phase motors have zero starting torque

Ans.

(c) capacitor Motor


Q.2

Which type of load is offered by cranes and hoist?

(a) Gradually varying load

(b) Non reversing, No load start

(c) Reversing, light start

(d) Reversing, Heavy start

Ans.

(d) Reversing, Heavy start


Q.3

The speed of a universal motor is
generally reduced by using

(a)gear trains

(b)V-belts

(c)brakes

(d)chains

Ans.

(a)gear trains


Q.4

Which of the following motors can be
used for unity power factor?

(a)Capacitor run motor

(b)Shaded pole motor

(c)Hysteresis motor

(d) Schrage motor

Ans.

(d) Schrage motor


Q.5

When a D.C. series motor is connected
to A.C. supply, the power factor will be
low because of

(a)high inductance .of field and ar-
mature circuits

(b)induced current in rotor due to
variations of flux

(c)fine copper wire winding

(d)none of the above

Ans.

(a)high inductance .of field and ar-
mature circuits


Q.6.

The direction of rotation of universal
motor can be reversed the by reversing
the flow of current through

(a)armature winding

(b)field winding

(c) either armature winding or field
winding

(d)none of the above

Ans.

(c) either armature winding or field
winding


Q.7

In which single-phase motor, the rotor
has no teeth or winding?

(a)Split phase motor

(b)Reluctance motor

(c)Hysteresis motor

(d)Universal motor

Ans.

(c)Hysteresis motor


Q.8

Which motor is normally free from
mechanical and magnetic vibrations?

(a)Split phase motor

(b)Universal motor

(c)Hysteresis motor

(d)Shaded pole motor

Ans.

(c)Hysteresis motor


Q.9

As hysteresis motors are free from
mechanical and magnetic vibrations
therefore these are considered as
suitable for

(a)fans

(b)blowers

(c)sound equipment

(d)mixer grinders

Ans.

(c)sound equipment


Q.10

A reluctance motor

(a)is self-starting

(b)is constant speed motor

(c)needs no D.C. excitation

(d) all of the above

Ans.

(d) all of the above


Q.11

In a hysteresis motor, the rotor must
have

(a)retentively

(b)resistivity

(c)susceptibility

(d)none of the above

Ans.

(c)susceptibility


Q.12

The rotor of a hysteresis motor is made
of

(a)aluminum

(b)cast iron

(c)chrome steel

(d)copper

Ans.

(c)chrome steel


Q.13

The electric motor used in portable
drills is

(a)capacitor run motor

(b)hysteresis motor

(c)universal motor

(d)repulsion motor

Ans.

(c)universal motor


Q.14

Which of the following applications
always have some load whenever
switched on?

(a)Vacuum cleaners

(6)Fan motors

(c)Pistol drills

(d)All of the above

Ans.

(c)Pistol drills


Q.15

The speed control of universal motor
used for sewing machines is by

(a)friction.

(b)varying the resistance

(c)tapping the field

(d)centrifugal mechanism

Ans.

(b)varying the resistance
Categories:

Question And Answer of Testing Of DC Machine | Electrical Machine Questions

Question And Answer of Testing Of DC Machine |  Electrical Machine Questions

Question And Answers related to Testing if DC Machine is important for GATE examination and also in competitive exams. All the important and basic questions are covered.

Question And Answer of Testing Of DC Machine |  Electrical Machine Questions


Q.1

One D.C. motor drives another D.C.
motor. The second D.C. motor when
excited and driven

(a)runs as a generator

(b)does not run as a generator

(c)also runs as a motor

(d)comes to stop after sometime

Ans.

 (a)runs as a generator

Q.2

Which of the following D.C. motors has
the least drop in speed between no-load
and nominal load?

(a)Series motor without commutating
poles

(b)Series motor with commutating
poles.

(c)Shunt motor with commutating
pole

(d)Compound motor without com-
mutating poles

Ans.

 (c)Shunt motor with commutating
pole

Q.3

The speed of a series motor at no load
is

(a)infinity

(b)4000r.p.m.

(c)2000r.p.m.

(d)1000r.p.m.

(e)none of the above

Ans.

 (a)infinity

Q.4

In a D.C. motor if the back e.m.f.is
absent

(a)motor will burn

(b)motor will not run at all

(c)motor will run at very slow speed

(d)motor will run at very high speed

Ans.

 (a)motor will burn

Q.5

A series motor is started without load.
The effect is that

(a)the back e.m.f. decreases

(b)the torque increases rapidly

(c)the speed increases rapidly

(d)the current drawn increases rapidly

Ans.

 (c)the speed increases rapidly

Q.6

What will happen if supply terminals
of D.C. shunt motor are interchanged?

(a)The direction of rotation will
reverse

(b)Motor will stop

(c)Motor will run at speed lower than
the normal speed in the same direc-
tion

(d) Motor will run at its normal speed
in the same direction as it was run-
ning

Ans.

 (d) Motor will run at its normal speed
in the same direction as it was run-
ning

Q.7

When the electric train is moving down
a hill the D.C. motor act as

(a)D.C. series generator

(b)D.C. shunt generator

(c)D.C. shunt motor

(d)D.C. series motor

Ans.

 (a)D.C. series generator

Q.8

Which of the following methods is most
economical for finding the no-load losses of a large D.C.. shunt motor?

(a)Retardation test

(b)Swinburne's test

(c)Hopkinson's test

(d)none of the above

Ans.

 (b)Swinburne's test

Q.9

Which of the following statement is in-
correct ? If a starter is not used with
large D.C. motor, it will draw a starting
current which

(a)will produce very low starting
torque

(b)will produce excessive line voltage
drop

(c)will damage the commutator

(d)is many times its full-load current

Ans.

 (a)will produce very low starting
torque

Q.10

The rated speed of a given D.C. shunt
motor is 900r.p.m.To run this machine
at 1000r.p.m., which of the following
speed control scheme will be used?

(a)Ward-Leonard control

(b)Armature current resistance control

(c)Field resistance control

(d)None of the above

Ans.

 (c)Field resistance control

Q.11

In electric motors carbon brushes are
used to

(a)provide a path for flow of current

(b)prevent sparking during commuta-
tion

(c)prevent overheating of armature
windings

(d)brush off carbon deposits on the
commutator

Ans.

 (a)provide a path for flow of current

Q.12

What is the effect produced by the
electric current in an electric motor?

(a)Heating effect only

(b)Magnetic effect only

(c)Heating as well as magnetic effect

(d)Heating as well as chemical effect

Ans.

 (c)Heating as well as magnetic effect

Q.13

In a motor, energy conversion would
not have been possible but for the

(a)production of opposing back e.m.f.
Eb in the armature

(b)input energy from supply

(c)use of commutator

(d)application of Fleming's left-hand
rule

Ans.

 (a)production of opposing back e.m.f.
Eb in the armature

Q.14

In a D.C. motor, unidirectional torque
is produced with the help of

(a)end plates

(b)bushes

(c)commutator

(d)both(b)and(c)

Ans.

 (d)both(b)and(c)

Q.15

In a D.C. motor, the ratio Eo/Va indi-
cates

(a)running torque of the motor

(b)starting torque of the motor

(c)efficiency of the motor

(d)speed regulation of the motor

Ans.

 (c)efficiency of the motor


Categories:

MCQs | Magnetic Field Q & A | Electrical Engineering Questions

MCQs | Magnetic Field Q &  A  |  Electrical Engineering Questions

Question And Answer related to magnetic field is provided in this post which will helpful in GATE examination and also in all type of competitive exams.

MCQs | Magnetic Field Q &  A  |  Electrical Engineering Questions



Q.1

Tesla is a unit of

(a)field strength

(b)inductance

(c)flux density

(d)flux.

Ans.

 (c)flux density
Q.2

A permeable substance is one

(a)which is a good conductor

(b)which is a bad conductor

(c)which is a strong magnet

(d)through which the magnetic lines of
force can pass very easily

Ans.

(d)through which the magnetic lines of
force can pass very easily


Q.3

The materials having low retentively
are suitable for making

(a)weak magnets

(b)temporary magnets

(c)permanent magnets

(d)none of the above

Ans.

 (b)temporary magnets
Q.4

A magnetic field exists around

(a)iron

(b)copper

(c)aluminum

(d)moving charges

Ans.

 (d)moving charges
Q.5

A magnet does not attract

(a)cobalt

(b)nickel

(c)copper

(d)iron

Ans.

 (c)copper
Q.6

Aluminum and. platinum are_____
materials.

(a)ferromagnetic

(b)diamagnetic

(c)paramagnetic

(d)insulating

Ans.

 (c)paramagnetic

 Q.7

Ferrites are _____materials.

(a)paramagnetic

(b)diamagnetic

(c)ferromagnetic

(d)none of the above

Ans.

 (c)ferromagnetic
Q.8

Air gap has......reluctance as compared
to iron or steel path

(a)little

(b)lower

(c)higher

(d)zero

Ans.

 (b)lower
Q.9

The direction of magnetic lines of force
is

(a)from south pole to north pole

(b)from north pole to south pole

(c)from one end of the magnet to
another

(d)none of the above

Ans.

 (b)from north pole to south pole
Q.10

Which of the following is a vector quantity?

(a)Relative permeability

(b)Magnetic field intensity

(c)Flux density

(d)Magnetic potential

Ans.

 (b)Magnetic field intensity
Q.11

The two conductors of a transmission
line carry equal current I in opposite
directions. The force on each conductor
is

(a)proportional to I

(b)proportional to (I)^2

(c)proportional to distance between
the conductors

(d)inversely proportional to I

Ans.

 (b)proportional to (I)^2
Q.12

A material which is slightly repelled by
a magnetic field is known as

(a)ferromagnetic material

(b)diamagnetic material

(c)paramagnetic material

(d)conducting material

Ans.

 (b)diamagnetic material
Q.13

When an iron piece is placed in a mag-
netic field

(a)the magnetic lines of force will bend
away from their usual paths in
order to go away from the piece

(b)the magnetic lines of force will bend
away from their usual paths in
order to pass through the piece

(c)the magnetic field. will not be affected

(d)the iron piece will break

Ans.

 (b)the magnetic lines of force will bend
away from their usual paths in
order to pass through the piece
Q.14

Fleming's left hand rule is used to find

(a)direction of magnetic field due to
current carrying conductor

(b)direction of flux in a solenoid

(c)direction of force on a current car-
rying conductor in a magnetic field

(d)polarity of a magnetic pole

Ans.

 (c)direction of force on a current car-
rying conductor in a magnetic field
Q.15

The ratio of intensity of magnetization.
to the magnetization force is known as

(a)flux density

(b)susceptibility

(c)relative permeability

(d)none of the above

Ans.

 (b)susceptibility


Categories:

Battery And Electrolysis | MCQs | Electrical ViVa Questions

Battery And Electrolysis | MCQs | Electrical ViVa Questions


There are Questions and Answers of battery and electrolysis provide which is more important to ask in viva and more important for interview questions and also in gate examination preparation.

Battery And Electrolysis | MCQs | Electrical ViVa Questions


Q.1

In constant-current charging method,
the supply voltage from discharged to
fully charged condition

(a)decreases

(b)increases

(c)remains constant

(d)none of the above

Ans.

 (b)increases
Q.2

Battery charging equipment is general-
ly installed

(a)in well ventilated location

(b)in clean and dry place

(c)as near as practical to the battery
being charged

(d)in location having all above features

Ans.

 (d)in location having all above features
Q.3

7.63.Followmg will happen if the specific
gravity of electrolyte becomes more
than 1.23

(a)Loss of capacity

(b)Loss of life

(c)Corrosion of the grids of the plate

(d)All above

Ans.

 (d)All above
Q.4

Batteries are charged by

(a)rectifiers

(b)engine generator sets

(c)motor generator sets

(d)any one of the above methods

Ans.

 (d)any one of the above methods
Q.5

Cell short circuit results in

(a)low sp. gravity electrolyte

(b)abnormal high temperature

(c)reduced gassing on charge

(d)all above

Ans.

 (d)all above
Q.6

Internal resistance of a cell is reduced
by

(a)using vent plug to permit gas
formed during discharge

(b)increasing the plate area

(c)putting plates very close together

(d)all above methods

Ans.

 (d)all above methods
Q.7

Capacity of dry cells is

(a)more when it is supplying current
for intermittent periods

(b)more when it is supplying current
for continuous periods

(c)unaffected by the type of discharge

(d)none of the above

Ans.

 (a)more when it is supplying current
for intermittent periods
Q.8

Battery container should be acid resis-
tance, therefore it is made up of

(a)glass

(b)plastic

(c)wood

(d)all above

Ans.

 (d)all above
Q.9

Sulphated cells are indicated by

(a)the loss of capacity of the cell

(b)the decrease of the specific gravity

(c)the low voltage of the cell on dis-
charge

(d)all above conditions

Ans.

 (d)all above conditions
Q.10

In a lead-acid cell, if the specific gravity
of sulphuric acid is 1.8,it will require
following ratio of acid to water to get
mixture of specific gravity of 1.3

(a)6 parts of acid to 4 parts of water

(b)4 parts of acid to 4 parts of water

(c)4 parts of acid to 6.parts of water

(d)4 parts of acid to 8 parts of water

Ans.

 (c)4 parts of acid to 6.parts of water
Q.11

Local action in a battery is indicated by

(a)excessive gassing under load conditions

(b)excessive drop in the specific
gravity of electrolyte even when the
cell is on open circuit

(c)both(a)and (b).

(d)none of the above'.

Ans.

 (d)none of the above
Q.12

Following will happen if battery charg-
ing rate is too high

(a)excessive gassing will occur

(b)temperature rise will occur

(c)bulging and buckling of plates will
occur

(d)all above will occur.

Ans.

 (d)all above will occur.
Q.13

Internal resistance of a cell is due to

(a)resistance of electrolyte

(6)electrode resistance

(c)surface contact resistance between
electrode and electrolyte

(d)all above

Ans. 

 (d)all above
Q.14

If a battery is wrongly connected on
charge following will happen

(a)current delivered by the battery
will be high

(6)current drawing will be nil

(c)current drawing will be very small

(d)current drawing will be very high

Ans.

 (d)current drawing will be very high
Q.15

In order that a hydrometer may float
vertically in electrolyte its C.G. should
be

(a)lowered

(b) raised

(c)undisturbed

(d)displaced sideways

Ans.

 (a)lowered
Categories:

Capacitance | Electric Field | Questions and Answers | Electrical Questions

Capacitance | Electric Field | Questions and Answers | Electrical Questions


There are many Questions and Answers provided regarding to electric field and capacitance, which will be more helpful in electrical viva questions and also in GATE examination for all electrical engineer.


Capacitance | Electric Field | Questions and Answers | Electrical Questions


Questions and Answers


Q.1. The electric field intensity at a point
situated 4 meters from a point charge
is 200 N/C. If the distance is reduced to
2 meters, the field intensity will be

(a)400N/C

(b)600N/C

(c)800N/C

(d)1200N/C

Ans. 

(c)800N/C


Q.2. Electric intensity(E)at any point in an
electric field is equal to

(a)potential gradient

(6)(potential gradient)2

(c)(potential gradient)1/2

(d)(potential gradient)1/3

Ans.

(a)potential gradient


Q.3. The lines of force due to charged par-
ticles are

(a)always straight

(b)always curved

(c)sometimes curved

(d)none of the above

Ans.

(b)always curved


Q.4. The electric field at a point situated at
a distance d from straight charged con-
ductor is

(a)proportional to d

(b)inversely proportional to d

(c)inversely proportional to d

(d)none of the above

Ans.

(b)inversely proportional to d


Q.5. The direction of electric field due to
positive charge is

(a)away from the charge

(b)towards the charge

(c)both(a)and(b)

(d)none of the above

Ans.

(a)away from the charge


Q.6. A field line and an equipotential sur-
face are

(a)always parallel

(b)always at 90

(c)inclined at any angle 0

(d)none of the above

Ans.

(b)always at 90


Q.7. The ability of charged bodies to exert
force on one another is attributed to the
existence of

(a)electrons

(b)protons

(c)neutrons

(d)electric field

Ans.

(d)electric field


Q.8. If the sheet of a Bakelite is inserted
between the plates of an air capacitor,
the capacitance will

(a)decrease

(b)increase

(c)remains unchanged

(d)become zero

Ans.

(b)increase


Q.9. A capacitor stores 0.24 coulombs at 10
volts. Its capacitance is

(a)0.024F

(b)0.12F

(c)0.6F

(d)0.8F

Ans.

(a)0.024F


Q.10 For making a capacitor, it is better to
select a dielectric having

(a)low permittivity

(b)high permittivity

(c)permittivity same as that of air

(d)permittivity slightly more than that
of air

Ans.

(b)high permittivity


Q.11. The units of capacitance are

(a)volts/coulomb

(b)coulombs/volt

(c)ohms

(d)henry/Wb

Ans.

(b)coulombs/volt


 Q.12. If three 15 uF capacitors are connected
in series, the net capacitance is

(a)5uF

(b)30 uF

(c)45 uF

(d)50 uF

Ans.

(a)5uF


Q.13. If three 10 uF capacitors are connected
in parallel, the net capacitance is

(a)20 F

(b)30uF

(c)40uF

(d)50 uF

Ans.

(b)30uF


Q.14. A dielectric material must be

(a)resistor

(b)insulator

(c)good conductor

(d)semi conductor

Ans.

(b)insulator


Q.15. An electrolytic capacitor can be used for

(a)D.C. only

(b)A.C. only,

(c)both D.C.as well as A.C.

Ans.

(a)D.C. only


Q.16. The capacitance of a capacitor is not
affected by

(a)distance between plates

(b)area of plates

(c)thickness of plates

(d)all of the above

Ans.

(c)thickness of plates


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Network Theorems | Questions and Answers 1 | Electrical Viva Questions

Network Theorems | Questions and Answers 1 | Electrical Viva Questions

Very helpful Questions and Answers are included related to network theorems which will helpful in GATE exam as well as competitive exam and Electrical Viva questions.


Network Theorems | Questions and Answers 1 | Electrical Viva Questions


Questions and Answers


Q.1. Kirchoff's current law states that

(a)net current flow at a junction is positive

(b)algebraic sum of current meeting at a junction is zero

(c)no current can leave the junction without some current entering it.

(d) total sum of the current meeting at the junction is zero.

Ans.

(b)algebraic sum of current meeting at a junction is zero


Q.2.  According to Kirchhoff's voltage law,
the algebraic sum of all IR drops and
e.m.f. in any closed loop of a network
is always

(a)negative

(b)positive

(c)determined by battery e.m.f.

(d)zero

Ans.

(d)zero


Q.3. Kirchhoff's current law is applicable to
only

(a)junction in a network

(b)closed loops in a network

(c)electric circuits

(d)electronic circuits

Ans.

(a)junction in a network


Q.4. Kirchhoff's voltage law is related to

(a)junction currents

(b)battery e.m.f.

(c)IR drops

(d)both(b)and(c)

(e)none of the above

Ans.

(d)both(b)and(c)


Q.5. Superposition theorem can be applied
only to circuits having

(a)resistive elements

(b)passive elements

(c)non-linear elements

(d)linear bilateral elements

Ans.

(d)linear bilateral elements


Q.6. The concept on which Superposition
theorem is based is

(a)reciprocity

(b)duality

(c)non-linearity

(d)linearity

Ans.

(d)linearity


Q.7. An ideal voltage source should have

(a)large value of e.m.f.

(b)small value of e.m.f.

(c)zero source resistance

(d)infinite source resistance

Ans.

(c)zero source resistance


Q.8. For a voltage source

(a)terminal voltage is always lower
than source e.m.f.

(b)terminal voltage cannot be higher
than source e.m.f.

(c)the source e.m.f.and terminal volt-
age are equal

Ans.

(b)terminal voltage cannot be higher
than source e.m.f.


Q.9. To determine the polarity of the voltage
drop across a resistor,it is necessary to
know

(a)value of current through the resistor

(b)direction of current through the
resistor

(c)value of resistor

(d)e.m.fs.in the circuit

Ans.

(b)direction of current through the
resistor


Q.10. 'maximum power output is obtained 
from a network when the load resis- 
tance is equal to the output resistance 
of the network as eeen from the ter- 
minals of the load". The above state- 
ment is associated with 

(a) Millman's theorem 

(b) Thevenin's theorem 

(c) Superposition the«»rem 

(d) Maximum power transfer theorem

Ans.

(d) Maximum power transfer theorem


Q.11.  "Any number of current sources in 
paralleFmay be replaced bw single 
current source whose current is the al- 
gebraic sum of individual source cur- 
rents and source resistance is the 
parallel combination of indiviaualsource resistances". 
The above etatement is associated with 

(a)Thevenin's theorem 

(b) Millman's theorem 

(c) Maximum power transfer theorem

(d) None of the above 

Ans.

(b) Millman's theorem 


Q.12. 'Tn any linear bilateral network, if a 
source of e. m, f.. E in any branch 
produces a current I in any other 
branch, then same e. m. f. Acting in the 
second branch would produce the samecurrent I in the first branch". 
The above statement is associated with 

(a) compensation theorem 

(b) superpositi on theorem 

(c) reciprocity theorem 

(d) none of the above 

Ans.

(a) compensation theorem 


Q.13. A linear resistor havingO<R<oo is a

(a)current controlled resistor

(b)voltage controlled resistor

(c)both current controlled and voltage
controlled resistor

(d)none of the above

Ans.

(c)both current controlled and voltage
controlled resistor

Q.14. A delta circuit has each element of value R/2. The equivalent element of star circuit with be

(a)R/6

(b)R/3

(c)2R

(d)3R

Ans.

(b)R/3

Q.15. The superposition theorem required as many circuits to be solved as there are

(a)sources, nodes and meshes

(b)sources and nodes

(c)sources

(d)nodes

Ans.

(c)sources



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