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Worksheets

MCQ EE

Total questions: 90

Worksheet time: 45mins

Name
Class
Date
1.

Which of the following is the unit of magnetic flux density?

a)

Weber/meter

b)

Tesla

c)

Newton/ampere-metre

d)

All of the above

2.

The magnetism of a magnet is due to

a)

earth

b)

cosmic rays

c)

due to pressure of big magnet inside the earth

d)

spin motion of electrons

3.

Which of the following materials is the most suitable for making a permanent magnet?

a)

Soft Iron

b)

Nickel

c)

Copper

d)

Steel

4.

A material is placed in a magnetic field. If it is thrown out of the field then the material is______

a)

Paramagnetic

b)

Ferromagnetic

c)

Diamagnetic

d)

Non-magnetic

5.

Which among the following is true about Faraday’s law of Induction?

a)

An emf is induced in a conductor when it cuts the magnetic flux

b)

An emf is induced in a conductor when it moves parallel to the magnetic field

c)

An emf is induced in a conductor when it moves perpendicular to the magnetic field

d)

An emf is induced in a conductor when it is just entering a magnetic field

6.

What is proportional to the magnitude of the induced emf in the circuit?

a)

Rate of change of current in the circuit

b)

Rate of change of resistance offered

c)

Rate of change of magnetic flux

d)

Rate of change of voltage

7.

A magnetic compass will be deflected if it is kept near a

a)

Magnet

b)

Charge at rest

c)

Both

d)

None

8.

Which one of the following material is most suitable for making core of an electromagnet?

a)

Air

b)

Steel

c)

Cu-Ni alloy

d)

Soft iron

9.

Transformer works on ______ principle.

a)

Gauss’s law

b)

Fleming’s right-hand rule

c)

Faraday’s law of electromagnetic induction

d)

Fleming’s left-hand rule

10.

A step-up transformer has _____ number of turns on primary winding and _____ number of turns on secondary winding.

a)

Less, More

b)

More, More

c)

More, Less

d)

Less, Less

11.

A transformer is a _____ device.

a)

Static and Dynamic

b)

Dynamic

c)

Static

d)

None of the above

12.

In a current transformer _____ winding is closed.

a)

Primary

b)

Secondary

c)

Both a & b

d)

None of the above

13.

In a transformer the relation between the input frequency and the output frequency on secondary winding is _____.

a)

Same

b)

Increases

c)

Decreases

d)

Increases and decreases with time

14.

Copper losses in a transformer are measured using _____.

a)

Open-circuit test

b)

Closed-circuit test

c)

Both a & b

d)

None of the above

15.

Transformer core lamination is made up of _____.

a)

Silicon steel

b)

Aluminium

c)

Cast iron



d)

Cast steel


16.

What is the functionality of a breather in a transformer?

a)

It is the transformer oil filter

b)

It absorbs the moisture of air during breathing

c)

Both a & b

d)

Passes cold air to the transformer

17.

What is basic functionality of a transformer?

a)

Voltage to current converter

b)

Current to voltage converter

c)

Frequency converter

d)

None of the above

18.

What are the two types of Instrument transformer?

a)

Voltage transformer

b)

Current transformer

c)

Potential transformer

d)

Both b and c

19.

The core of a transformer is laminated for _____ reason

a)

Minimize hysteresis loss

b)

Minimize eddy & hysteresis current loss

c)

Lowers eddy current loss

d)

Copper loss

20.

Which losses in a transformer is zero at full load?

a)

Eddy current loss

b)

Copper loss

c)

Friction loss

d)

Core loss

21.

A transformer has _____ resistance between its primary and secondary winding.

a)

Infinity

b)

0.1 ohm

c)

100 ohm

d)

0

22.

The rating of a transformer is expressed as_____.

a)

Ampere

b)

KVAR

c)

Kilowatts

d)

Kilo-volt-ampere

23.

What is the purpose of oil in an oil-filled transformer?

a)

Insulate

b)

Resistance

c)

Cooling

d)

Both a & c

24.

Which test is used to determine iron losses in a transformer?

a)

SC test

b)

OC test

c)

Both SC & OC

d)

None of the above

25.

Which of the following component is not related to the transformer?

a)

Breather

b)

Exciter

c)

Buchholz relay

d)

Conservator

26.

Which component of the transformer causes noise?

a)

Iron core which contains magnetostriction

b)

Fan that is used for cooling purpose

c)

Vibration due to mechanical motion

d)

All the above

27.

The relation between primary and secondary flux in a transformer is ________.

a)

Primary flux and secondary flux are equal

b)

Primary flux is less than the secondary flux

c)

Primary is greater than the secondary flux

d)

None of the above

28.

If the direct current is supplied to a transformer, what happens to a transformer.

a)

Transformer operates with low efficiency

b)

Transformer operates with greater efficiency

c)

Transformer stops working due to damage that occurred

d)

Transformer operates normally

29.

How much percent of friction loss is present in a transformer?

a)

0%

b)

5%

c)

3%

d)

1%

30.

Which transformer has primary and secondary winding coupled electrically and magnetically?

a)

Potential transformer

b)

Current transformer

c)

Auto transformer

d)

Power transformer

31.

The volatility and viscosity values of an oil transformer should be _________.

a)

High, High

b)

Low, Low

c)

Low, High

d)

High, Low

32.

On which parameter does the core size of a transformer depends?

a)

Only frequency

b)

Only core area

c)

Cores area and frequency

d)

None of the above

33.

Which of the following is the advantage of a transformer?

a)

It is a stationary device

b)

It provides high efficiency

c)

No starting time is required

d)

All the above

34.

Which substance is used in the transformer breather component?

a)

Potassium

b)

Sodium

c)

Silica sand

d)

Silica gel

35.

The core of a transformer is constructed using ________.

a)

Silicon steel

b)

Steel

c)

Zinc

d)

Wood

36.

What is the purpose of a conservator in a transformer?

a)

Protects against short circuit

b)

Prevents moisture entry

c)

Controls the transformer oil which expands and contracts based on environmental temperature

d)

None of the above

37.

The lamination thickness of a transformer is______.

a)

6 mm to 8 mm

b)

0.4 mm to 0.5 mm

c)

2.5 mm to 5 mm

d)

0.1mm to 0.2 mm

38.

Buchholz relays warns about______.

a)

Electrical faults that occur within the transformer

b)

Electrical faults that occur in the surroundings of a transformer

c)

Both a and b

d)

None of the above

39.

Which test is least done on a transformer?

a)

Radio interface test

b)

OC test

c)

SC test

d)

None of the above

40.

The purpose of Silicon steel in a transformer core is to __

a)

Increase eddy current loss

b)

Reduce hysteresis loss

c)

Maintain eddy current losses

d)

None of the above

41.

Which parameter in a transformer remains the same?

a)

Resistance

b)

Frequency

c)

Voltage

d)

All the above

42.

Which type of core is used in a transformer with high frequency?

a)

Cast Fe core

b)

CU core

c)

Fe core

d)

Air core

43.

The emf equation of a transformer has _____ value of flux.

a)

Zero

b)

Minimum

c)

Equal

d)

Maximum

44.

What is the advantage of autotransformer over dual transformer?

a)

Low power

b)

Half load

c)

Less winding materials

d)

None of the above

45.

SI units of EMF

a)

Centimetres

b)

Hertz

c)

Amperes

d)

Volts

46.

SI unit of power

a)

Joule

b)

Watt

c)

Centimetres

d)

Hz

47.

Units of electric field

a)

Centimetres

b)

Volts / Meter

c)

Amperes

d)

Volts

48.

What is Np in a transformer?

a)

Number of turns on both primary and secondary winding

b)

Number of turns on the secondary winding

c)

Number of turns on the primary winding

d)

None of the above

49.

What is Ns in a transformer?

a)

Number of turns on the secondary winding

b)

Number of turns on the primary winding

c)

Number of turns on both primary and secondary winding

d)

None of the above

50.

SI unit of magnetic field strength (H)

a)

Amperes

b)

Centimetres

c)

Volts

d)

Amp / Meter

51.

SI unit of magnetic Flux

a)

Centimetres

b)

Amp / Meter

c)

Weber

d)

Amperes

52.

Faradays Law equation

a)

E = N dφ

b)

E = N dφ / dt

c)

E = N dt

d)

N dφ = dt

53.

At what condition does an ideal transformer gives maximum efficiency?

a)

Copper loss = 0

b)

Copper loss = 99%

c)

Copper loss = infinity

d)

Copper loss = iron loss

54.

Which component is visible from outside a transformer?

a)

Wires

b)

Core

c)

Windings

d)

Brushes

55.

What happens to transformer windings if operated continuously?

a)

Temperature decreases

b)

Temperature increases

c)

Resistance increases

d)

None of the above

56.

Which part of the transformer is damaged by overheating?

a)

Winding insulation

b)

Brushes

c)

Frame

d)

Core

57.

A transformer transform

a)

Voltage

b)

Frequency

c)

Voltage & current

d)

Current

58.

A transformer

a)

Changes ac to dc

b)

Changes dc to ac

c)

Steps up or down dc voltages

d)

Steps up or down ac voltages

59.

The primary winding of a transformer has a 120 V ac supply. What is the value of secondary voltage if the turn ratio is 10?

a)

12000 V

b)

12 V

c)

1200 V

d)

120 V

60.

A Buchholz relay can be installed on


a)

Welding transformers

b)

Oil cooled transformers

c)

Autotransformers

d)

Air-cooled transformers

61.

Lamination’s of the transformer core are generally made of

a)

case iron

b)

carbon

c)

silicon steel

d)

stainless steel

62.

The resistance of armature winding depends on

a)

length of conductor

b)

cross-sectional area of the conductor

c)

number of conductors

d)

all of the above

63.

The field coils of D.C. generator are usually made of

a)

mica

b)

copper

c)

cast iron

d)

carbon

64.

The commutator segments are connected to the armature conductors by means of

a)

copper lugs

b)

resistance wires

c)

insulation pads

d)

brazing

65.

In D.C. generators the pole shoes are fastened to the pole core by

a)

brazing

b)

screws

c)

rivets

d)

welding

66.

Fleming’s right-hand rule regarding direction of induced e.m.f., correlates

a)

magnetic flux,direction of current flow and resultant force

b)

magnetic flux,direction of motion and the direction of e.m.f. induced

c)

magnetic field strength, induced voltage and current

d)

magnetic flux, direction of force and direction of motion of conductor

67.

While applying Fleming’s right-hand rule to And the direction of induced e.m.f., the thumb points towards

a)

direction of induced e.m.f.

b)

direction of flux

c)

direction of motion of the conductor if forefinger points in the direction of generated e.m.f

d)

direction of motion of conductor, if forefinger points along the lines of flux

68.

The bearings used to support the rotor shafts are generally

a)

ball bearings

b)

bush bearings

c)

magnetic bearmgs

d)

needle bearings

69.

In D.C. generators, the cause of rapid brush wear may be

a)

severe sparking

b)

rough commutator surface

c)

imperfect contact

d)

any of the above

70.

In a four-pole D.C. machine

a)

all the four poles are north poles

b)

alternate poles are north and south

c)

all the four poles are south poles

d)

two north poles follow two south poles

71.

The function of pole shoes in the case of D.C. machine is

a)

to reduce the reluctance of the magnetic path

b)

to spread out the flux to achieve uniform flux density

c)

to support the field coil

d)

to discharge all the above functions

72.

Permeance is the reciprocal of

a)

flux density

b)

reluctance

c)

ampere-turns

d)

resistance

73.

In a D.C. machine stray loss is the sum of

a)

total copper loss and mechanical loss

b)

armature copper loss and iron loss

c)

shunt field copper loss and mechanical loss

d)

iron loss and mechanical loss

74.

D.C. generator works on the principle of

a)

Faraday's law of electromagnetic induction

b)

Lenz’s law

c)

Ohm’s law

d)

none of the above

75.

D.C. generator can be considered as

a)

rectifier

b)

prime mover

c)

rotating amplifier

d)

power pump

76.

Following components of a D.C, generator plays an important role in providing direct current from DC generator?

a)

Dummy coils

b)

Commutator

c)

Eye bolt

d)

Equalizer rings

77.

Magnetic field in a dc generator is normally produced by

a)

electromagnets

b)

permanent magnets

c)

both (a) and (b)

d)

none of above

78.

Direction of rotation of motor is determined by ____________

a)

Faraday’s law

b)

Lenz’s law

c)

Coulomb’s law

d)

Fleming’s left-hand rule

79.

In a dc compound motor, the field regulator is provided to

a)

control the flux

b)

limit the armature current.

c)

demagnetize field partially.

d)

none of the above

80.

Which part will surely tell that given motor is DC motor and not an AC MOTOR?

a)

Winding

b)

Shaft

c)

Commutator

d)

d) Stator

81.

Field weakening control method is used for the speed _________

a)

Above rated speed

b)

Below rated speed

c)

Can be used anywhere

d)

d) Can’t tell

82.

Armature resistance control method is used for the speed _____________

a)

Above rated speed

b)

b) Below rated speed

c)

c) Can be used anywhere

d)

d) Can’t tell

83.

Why field winding of a DC series motor is provided with thick wire?

a)

As it carries large load current

b)

b) To provide large flux

c)

c) In order to reduce eddy current to provide large flux

d)

d) To reduce the of insulting materials

84.

The speed of a DC shunt motor can be increased by ______

a)

Increasing the resistance in the armature circuit

b)

b) Increasing the resistance in the field circuit

c)

c) Reducing the resistance in the field circuit

d)

d) Reducing the resistance in the armature circuit

85.

Which of the following loss is likely to have the highest proportion at the rated load of the DC generator?

a)

Hysteresis loss

b)

Field copper loss

c)

Armature copper loss

d)

Eddy current loss

86.

In a DC generator, the iron losses mainly take place in ____________

a)

a) Yoke

b)

Commutator

c)

Armature Core

d)

Armature conductors

87.

In the DC motor the iron losses occur in __________

a)

Field

b)

Commutator

c)

Brushes

d)

Armature Core

88.

Which of the following load normally need starting torque more than the rated torque?

a)

Conveyors

b)

Blowers

c)

Air compressor

d)

Centrifugal pump

89.

In which of the ffollowing applications DC series motor is used?

a)

Centrifugal Pump

b)

Water pump drive

c)

CPU fan

d)

Cranes for lifting heavy loads

90.

Nowadays DC motor is widely used in

a)

Electric Traction

b)

Machine shop

c)

Centrifugal Pump

d)

Air compressor

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