EASY PSC | Kerala PSC 050/2022 - Electrician Answer Key Published

Question 1

The property of a conductor due to which it passes electric current is called

A

Inductance

B

Capacitance

C

Reluctance

D

Conductance

Question 2

Which of the following materials has negative temperature co-efficient of resistance?

A

Gold

B

Brass

C

Carbon

D

Manganin

Question 3

A rheostat differs from potentiometer in the respect that it

A

Has lower wattage ratings

B

Has higher wattage ratings

C

Has large number of tappings

D

Has large number of turns

Question 4

1 Coulomb charge equals to the charge on

A

(A)

B

(B)

C

(C)

D

(D)

Question 5

An instrument which detects electric current flow is known as

A

Frequency meter

B

Odometer

C

Galvanometer

D

Rheostat

Question 6

The resistance of a conductor varies inversely as

A

Length

B

Resistivity

C

Diameter

D

Temperature

Question 7

Varistors act like

A

Linear resistors

B

Carbon resistors

C

Resistor with zero temperature co-efficient

D

Non-linear resistors

Question 8

Melting temperature of electrician's solder is

A

300°C

B

145°C

C

280°C

D

185°C

Question 9

Which of the following materials is good conductor of electricity?

A

Gold

B

Iron

C

Aluminium

D

Copper

Question 10

Maximum current carrying capacity of 1.5 mm2 aluminium wire

A

13A

B

10A

C

8A

D

12A

Question 11

Kirchhoff's law is applicable to

A

AC circuits only

B

DC circuits only

C

Passive network only

D

Both AC and DC circuits

Question 12

The circuit whose properties are same in either direction is known as

A

Unilateral circuits

B

Irreversible circuit

C

Bilateral circuit

D

Short circuit

Question 13

The capacity of a storage cell is expressed in

A

Ampere

B

Farad

C

Ampere hour

D

None of these

Question 14

Which of the following acts as depolarizer in Leclanche cell?

A

(A)

B

(B)

C

(C)

D

(D)

Question 15

Why Constantan wire is used for making standard resistors?

A

High resistivity

B

Low resistivity

C

Low temperature co-efficient of resistance

D

High temperature co-efficient of resistance

Question 16

The capacity of a storage cell is 2.5 Ah. What is the maximum current that can supply for half hour?

A

0.5 A

B

1.8 A

C

2.5 A

D

5.0 A

Question 17

Sedimentation in lead acid batteries occurs due to

A

Overcharging at high rate

B

Slow charging at low rate

C

Over discharging

D

Non-utilization for longer periods

Question 18

The capacitance of a capacitor is not affected by

A

Thickness of the plates

B

Distance between plates

C

Area of plates

D

None of these

Question 19

According to Lenz's law the direction of induced current always

A

Aids the cause

B

Opposes the cause

C

Remains same

D

Equal to the cause

Question 20

Electrochemical equivalent is usually expressed in

A

Milligrams/Coulomb

B

Milligrams/Kw

C

Milligrams/Volt

D

Milligrams/kVAr

Question 21

Magnets are made of low retentivity but high permeability materials are called

A

Permanent magnets

B

Weak magnets

C

Electromagnets

D

Natural magnets

Question 22

The diamagnetic material has relative permeability

A

Less than 1

B

More than 1

C

More than 100

D

Equal to ferromagnetic material

Question 23

The unit of Magnetomotive force is

A

Ampere

B

Volt

C

Ampere turns/metres

D

Tesla

Question 24

Working principle of auto transformer is

A

Conduction

B

Induction

C

Both induction and conduction

D

Admittance

Question 25

Magnetic field exists around

A

Iron

B

Copper

C

Aluminium

D

Moving charges

Question 26

Fleming's left hand rule is used to find

A

Polarity of magnetic pole

B

Direction of force on a current carrying conductor in a magnetic field

C

Direction of magnetic field due to current carrying conductor

D

Direction of induced emf in solenoid

Question 27

Susceptability is positive for

A

Ferromagnetic materials

B

Diamagnetic materials

C

Paramagnetic materials

D

None of these

Question 28

The unit of capacitance is

A

Volts/Coulombs

B

Coulombs/Volt

C

Ohm-metre

D

None of these

Question 29

Internal resistance of a cell is due to

A

Electrode resistance

B

Resistance of electrolyte

C

Surface contact resistance between electrodes and electrolyte

D

All of the above

Question 30

When two resistors are connected in series they have

A

Same voltage across them

B

Same resistance value

C

Different resistance value

D

Same current passing through them

Question 31

Skin effect occurs when a conductor carries current at _______ frequencies

A

High

B

Low

C

Very low

D

Medium

Question 32

The pf of the following circuit will be unity

A

Resistive circuit

B

Inductive circuit

C

Capacitive circuit

D

Both (A) and (C)

Question 33

Form factor for a sine wave is

A

1.414

B

1.11

C

0.637

D

0.707

Question 34

In a series RLC circuit on resonance condition

A

VR = V

B

Z = R/2

C

VL = 0

D

XL = XC

Question 35

The load on each sub-circuit shall be restricted to

A

700 watts

B

800 watts

C

900 watts

D

3000 watts

Question 36

The length of the rod and pipe electrodes used for earthing shall not be less than

A

1 m

B

2.5 m

C

5 m

D

6 m

Question 37

During continuity test, dead short in an installation is indicated by megger

A

zero ohms

B

100 megohms

C

1 megohms

D

infinity

Question 38

The output rating of an alternator is expressed in

A

KW

B

KVA

C

HP

D

KVAR

Question 39

Batten wiring is recommended for

A

Temporary

B

Permanent

C

Industrial

D

Power

Question 40

The voltage wave form produced by alternator should be

A

Pulse wave

B

Sine wave

C

Triangular wave

D

Saw tooth wave

Question 41

In DC machines, mechanical losses are primarily function of

A

speed

B

voltage

C

current

D

none of the above

Question 42

Armature of a DC machine is made of

A

conducting material

B

insulating material

C

non-ferrous material

D

silicon steel

Question 43

Which DC motor has got maximum self loading property?

A

shunt motor

B

series motor

C

differentially compounded motor

D

cumulatively compounded motor

Question 44

When a DC series motor is connected to an AC supply, then

A

It will stop

B

It will run without any trouble

C

It may burn out

D

It will run with less efficiency and high spark at commutator

Question 45

For a 4 pole machine wave winding is impossible with armature conductors of

A

34

B

32

C

30

D

38

Question 46

Where is field winding mounted in a DC machine?

A

Stator

B

Rotor

C

Absent

D

Anywhere on stator or rotor

Question 47

In normal DC machines operating at full-load conditions, the most powerful electromagnet is

A

Field winding

B

Interpole winding

C

Interpole and compensating winding together

D

Armature winding

Question 48

When an electric train is moving down a hill, the DC motor will operate as

A

DC series motor

B

DC series generator

C

DC shunt motor

D

DC shunt generator

Question 49

Which of the following is not the function of pole shoe in DC motor?

A

To reduce eddy current loss

B

To reduce reluctance

C

To spread out flux

D

To support field coil

Question 50

In DC generators, the brushes on commutator remain in contact with conductors which

A

lie under south pole

B

lie under north pole

C

lie under interpolar region

D

are farthest from the poles

Question 51

Insertion of resistance in the rotor of an induction motor

A

changes the magnitude of maximum torque developed

B

changes the speed at which maximum torque is developed

C

changes both magnitude of a maximum torque developed and speed at which it occurs

D

nothing as above happens

Question 52

Torque developed by a single phase induction motor at starting is

A

uniform

B

pulsating

C

none of the two

D

nil

Question 53

An induction motor is identical to

A

D.C. compound motor

B

D.C. series motor

C

Synchronous motor

D

Asynchronous motor

Question 54

The efficiency of an induction motor can be expected to be nearly

A

60 to 90%

B

80 to 90%

C

92 to 95%

D

65%

Question 55

The cause of crawling in the induction motor is

A

Low voltage supply

B

High loads

C

Harmonics developed in the motor

D

Improper design of the machine

Question 56

The starting capacitor of a single phase motor is

A

Electrolytic capacitor

B

Ceramic capacitor

C

Paper capacitor

D

None of these

Question 57

In cylindrical rotor ________ portion of the rotor is wound.

A

one-third

B

two-third

C

one-half

D

whole

Question 58

In the circle diagram of an induction motor the diameter of circle represents the

A

rotor current

B

line voltage

C

operating torque

D

maximum torque

Question 59

In an induction motor, rotor slots are usually not quite parallel to the shaft but are given a slight skew

A

To reduce the magnetic hum

B

To reduce the locking tendency of the rotor

C

Both (A) and (B) above

D

To increase the speed of the motor

Question 60

For an induction motor, synchronous wattage means

A

Stator input in watts

B

Rotor output in watts

C

Rotor input in watts

D

Shaft output in watts

Question 61

Which of the following places is not associated with nuclear power plants in India?

A

Narora

B

Tarapur

C

Kota

D

Bangalore

Question 62

Equipment used for pulverizing the coal is known as

A

Ball mill

B

Hopper

C

Burner

D

Stoker

Question 63

The largest source of electricity in India is

A

Tidal power

B

Hydroelectric power

C

Nuclear power

D

Thermal power

Question 64

In francis turbine runner, the number of blades is usually of the order of

A

3-6

B

8-10

C

16-24

D

30-42

Question 65

Water hammer occurs in

A

surge tank

B

penstock

C

turbine casing

D

draft tube

Question 66

The modern steam turbines are

A

impulse turbines

B

reaction turbines

C

impulse-reaction turbines

D

none of the above

Question 67

Usually, the generated voltage in generating stations is

A

33 KV

B

11 KV

C

33 KV

D

66 KV

Question 68

The most economical power factor for a consumer is

A

0.9 lagging

B

0.9 leading

C

0.5 lagging

D

0.5 leading

Question 69

Load factor of a power station is generally

A

equal to unity

B

less than unity

C

more than unity

D

equal to zero diversity factor always

Question 70

In thermal power plant, turbine is placed

A

before boiler

B

in between boiler and generator

C

after generator

D

any of the above

Question 71

The usual spans with RCC poles are

A

30-50 metres

B

20-30 metres

C

80-100 metres

D

150-200 metres

Question 72

High voltage transmission lines use

A

suspension insulators

B

pin insulators

C

both (A) and (B)

D

none of the above

Question 73

Relays used in long transmission lines is

A

Impedance relay

B

Mho's relay

C

Reactance relay

D

None of the above

Question 74

The material commonly used for insulation in high voltage cables is

A

paper

B

lead

C

PVC

D

rubber

Question 75

66 KV is suitable for transmission of power over

A

200 km

B

120 km

C

60 km

D

30 km

Question 76

Bundled conductors in EHV transmission system provide

A

increased capacitance

B

reduced capacitance

C

increased inductance

D

increased voltage gradient

Question 77

Current flow through the neutral of three phase 4 wire cable is

A

equal to current in phase wires

B

equal to the sum of currents in phase wires

C

less than current in the phase wire

D

more than the current in the phase wire

Question 78

Skin effect results in

A

reduced effective resistance but increased effective internal reactance of the conductor

B

increased effective resistance but reduced effective internal reactance of the conductor

C

reduced effective resistance as well as effective internal reactance

D

increased effective resistance as well as effective internal reactance

Question 79

The most suitable practical value of primary distribution is

A

66 kV

B

6.6 kV

C

230 V/400 V

D

22 kV

Question 80

Which among the following properties has got a higher for aluminium in comparison to that of copper?

A

Electrical resistivity

B

Melting point

C

Thermal conductivity

D

Specific gravity

Question 81

The force producing movement of the pointer in an indicating instrument is called

A

Controlling force

B

Deflecting force

C

Damping force

D

Distracting force

Question 82

An instrument using gravity control will read correctly if used in

A

the vertical position only

B

an inclined position only

C

the horizontal position only

D

any position

Question 83

The deflecting torque of moving iron attraction type of instrument is _______

A

directly proportional to the current

B

inversely proportional to the current

C

directly proportional to the square of the current

D

inversely proportional to the square of the current

Question 84

Air is removed from incandescent lamp is to:

A

prevent oxidation

B

minimise heat loss

C

(A) and (B)

D

none of these

Question 85

Light energy radiated per second from a light source is called

A

Illumination

B

Luminance

C

Luminous intensity

D

Luminous flux

Question 86

A 60 w lamp given a luminous flux of 1500 lumen its efficiency is

A

1500 lumen/watt

B

25 lumen/watt

C

2.5 lumen/watt

D

250 lumen/watt

Question 87

The no load current of a transformer in terms of the full load current is usually

A

1 to 3%

B

5 to 9%

C

9 to 12%

D

12 to 20%

Question 88

The purpose of oil in the transformer is to

A

Lubricate

B

Insulate and cool

C

Lubricate and cool

D

Cool

Question 89

Buchholz relay is a protective device used in

A

3 phase motor

B

Single phase motor

C

Auto transformer

D

Power transformer

Question 90

Dynamometer type wattmeter can be used on

A

Both AC and DC

B

DC only

C

AC only

D

None of these

Question 91

The specification of ceiling fan is

A

Current

B

Voltage

C

Sweep

D

Power

Question 92

The gas filled in a sodium vapour lamp is

A

Neon

B

Helium

C

Argon

D

Hydrogen

Question 93

Which element is used as a semiconductor material?

A

Copper

B

Plastic

C

Brass

D

Silicon

Question 94

The main characteristic of any diode is

A

it lets current flow in only one direction

B

most current flow when it is reverse biased

C

it lets current flow from cathode to anode

D

no current flow when it is forward biased

Question 95

NPN transistors are preferred to PNP transistor for

A

easy use in +ve supply rail

B

higher switching speed

C

a wide range of operating temperature

D

the reasons mentioned in (A) and (B) above

Question 96

The number of depletion layers in a transistor is

A

Three

B

Two

C

One

D

Four

Question 97

The material used in an oven as heating element is

A

Copper

B

Brass

C

Eureka

D

Nichrome

Question 98

Which motor is generally used for domestic washing machine?

A

split phase motor

B

3 phase induction motor

C

capacitor start motor

D

reluctance motor

Question 99

An Ohm meter is used for measuring

A

resistance

B

insulation resistance

C

current

D

potential difference

Question 100

The rotating speed of the magneto type megger is

A

180 rpm

B

150 rpm

C

160 rpm

D

120 rpm

050/2022 - Electrician - Agriculture Development and Farmer's Welfare