EASY PSC | Kerala PSC 102/2022 - Tradesman (Electronics) Answer Key

Question 1

The resistance between the opposite faces of a metre cube of that material is known as :

A

Conductance

B

Resistance

C

Conductivity

D

Resistivity

Question 2

The ratio of the true power delivered to an AC circuit to the apparent power that the source must supply is called :

A

Inductive reactance

B

Power factor

C

Power of the circuit

D

Power ratio

Question 3

The power consumed in a pure capacitive circuit is :

A

Zero

B

Infinity

C

Maximum

D

Minimum

Question 4

The commercial unit of electrical energy is :

A

KW

B

KWH

C

WH

D

KVA

Question 5

The direction of induced current is obtained by :

A

Fleming’s right hand rule

B

Fleming’s left hand rule

C

Maxwell’s cork screw rule

D

Faraday’s laws of electromagnetic induction

Question 6

The resistance of a heater rated 2.2 KW and 220 v is :

A

220 Ω

B

440 Ω

C

2.2 Ω

D

22 Ω

Question 7

The total resistance of a parallel circuit compared to the low value of resistance connected in the circuit is :

A

Less (or) Equal

B

Equal

C

Greater

D

Less

Question 8

From the following which is equal to 1 Watt?

A

1 Farad

B

1 Ohm / Volt

C

1 Joule / Second

D

1 Volt / Ampere

Question 9

The SI unit of electric conductance is :

A

Ohm

B

Siemens

C

Coulomb

D

Candela

Question 10

A sine wave has a maximum value of 40 mv. The rms value of the sine wave is :

A

22.48

B

25.48

C

28.28

D

24.24

Question 11

An Oscilloscope shows 20 cycles of sine wave occurring in 2 milli seconds. The time period of the sine wave is :

A

0.01 milli seconds

B

0.001 milli seconds

C

0.1 milli seconds

D

0.0001 milli seconds

Question 12

In a pure parallel resonance circuit, with pure inductor and pure capacitor, at resonance the impedence will be :

A

Infinity

B

Zero

C

Maximum

D

Minimum

Question 13

The instrument used for measuring high voltage and high current is :

A

Digital Multimeter

B

Ammeter

C

Instrument Transformer

D

Megger

Question 14

The effect on Current Transformer (CT) if it’s secondary is kept open is :

A

CT primary burns out

B

Volt-Ampere capacity reduces

C

Volt-Ampere capacity increases

D

CT secondary winding burns out

Question 15

The colour coding of a resistor is Blue, Red, Yellow, Gold, Gold. It’s value is :

A

624Ω ± 5%

B

6.24KΩ ± 5%

C

62.4Ω ± 5%

D

62.4KΩ ± 5%

Question 16

In an AC supply system, to improve power factor :

A

By connecting inductive load in series

B

By connecting capacitors in series with the load

C

By connecting inductive loads in parallel

D

By connecting capacitor in parallel with load

Question 17

The following has it’s working based on electromagnetic induction :

A

Voltmeter

B

Transformer

C

Ammeter

D

Galvanometer

Question 18

A static device which increases or decreases AC voltage without changing the frequency of the supply is :

A

Alternator

B

Inverter

C

DC generator

D

Transformer

Question 19

When an alternating voltage is applied to a pure inductor, the resultant alternating current through the inductor is :

A

Leading by 90°

B

Lagging by 90°

C

Leading by 180°

D

Lagging by 180°

Question 20

If one thousand watts lamp is used for one hour, it consumes an energy of :

A

1 kwh

B

10 wh

C

0.1 kwh

D

0.01 wh

Question 21

The working principle of single phase induction motor is :

A

Joule’s law

B

Faraday’s Laws of electromagnetic induction

C

Lenz’s law

D

Faraday’s laws of electrolysis

Question 22

The magnetic field produces by a single phase induction motor is :

A

Rotating magnetic field

B

Stationary magnetic field

C

Steady magnetic field

D

Pulsuating magnetic field

Question 23

In an induction motor a measure of the difference between the machine’s synchronous speed and it’s shaft speed is :

A

Slip

B

Synchronous speed

C

Rotor speed

D

Stator speed

Question 24

The important property of Fuse wire is :

A

Low specific resistance and high melting point

B

High specific resistance and high melting point

C

High specific resistance and low melting point

D

Low specific resistance and low melting point

Question 25

The fuse rating is expressed in terms of :

A

Voltage

B

Power

C

Resistance

D

Current

Question 26

The Maximum reverse Voltage that can be applied to the Diode without destruction is :

A

Peak Inverse Voltage

B

Maximum Forward Voltage

C

Forward Voltage

D

Maximum Average Voltage

Question 27

The PIV of Full Wave Bridge Rectifier is :

A

2 Vm

B

3 Vm

C

Vm

D

4 Vm

Question 28

What is the Ripple factor of Half wave Rectifier?

A

0.482

B

1.21

C

0.472

D

1.22

Question 29

Both NPN and PNP Transistors are equally useful in electronics Circuits, However NPN Transistors are :

A

NPN Has High Doping Level

B

Big Size

C

Higher Switching Speed

D

Easily Operated

Question 30

The Forward Voltage Across the Base-Emitter PN Junction of Transistor is referred to as :

A

VEB

B

VCB

C

VCC

D

VCE

Question 31

The Maximum Permissible Collector Current IC (max) of Transistor BC 548 is :

A

20 mA

B

50 mA

C

200 mA

D

30 mA

Question 32

The Phase Relationship between Input and Output Wave forms in Common Emitter Configuration is :

A

0° Phase shift

B

180° Phase shift

C

270° Phase shift

D

90° Phase shift

Question 33

What is the meaning of first letter indicated in the Transistor Code Number BC 107?

A

Silicon Material is Used

B

Germanium Material is Used

C

Antimony Material is Used

D

Bizmuth Material is Used

Question 34

The Most Widely used type of biasing in Linear Transistor Circuit is :

A

Base Bias

B

Emitter Bias

C

Voltage divider Bias

D

Emitter feedback Bias

Question 35

All radios, tape recorders and Televisions invariably use Negative feedback in circuits for a function :

A

Automatic frequency Control

B

Automatic gain Control

C

Automatic Line Control

D

Automatic Level Control

Question 36

How the Maximum Permissible Collector-Base Voltage that can be Applied across Collector-Base is?

A

VCB(max)

B

VCE(max)

C

VEB(max)

D

VCC(max)

Question 37

Which Type of Package is used to Transistors Utilized for medium and Power amplifications?

A

Plastic Package

B

Metal Package

C

Ceramic Package

D

Plastic Package with Heat Sinks

Question 38

Which Coding System for Transistor type numbering system is followed by European Standard?

A

JIS Standard

B

Home code

C

JEDEC Standard

D

Pro-Electron Standard

Question 39

The type – Code Printed on a Zener is BZC9V1, the Letter ‘C’ indicates is :

A

Silicon

B

Zener

C

5% Tolerance

D

Voltage regulator

Question 40

JFET is Commonly Used as input amplifiers in Voltmeters, Oscilloscopes and other Measuring Devices, due to :

A

High Maximum Drain Source Voltage VGS

B

Maximum Forward gate Current IG

C

High Input Impedance

D

Low Input Impedance

Question 41

What is the Package type for JFET BFW10?

A

TO-72

B

TO-92

C

TO-82

D

TO-102

Question 42

What is the term Stands for TRIAC?

A

TRIode alternate Control

B

TRIode DC

C

TRIode AC Semiconductor

D

TRIode Access Console

Question 43

When a TRIAC is ON the Current flowing between MT1 and MT2 is known as?

A

Holding Current

B

Safe Current

C

Principal Current

D

Leakage Current

Question 44

The resistance between Anode and Cathode of SCR in Quick Test Method is :

A

Very low resistance

B

Infinite Resistance

C

Low Resistance

D

High Resistance

Question 45

How many Semiconductor Layers are used in UJT Fabrication?

A

3

B

2

C

4

D

1

Question 46

What is the advantage of MOSFET?

A

Slow Switching Speed

B

Fast Switching Speed

C

Higher Power gate Signal

D

Low thermal Ionisation of Electron-holes

Question 47

BJT is a Current driven device, whereas IGBT is driven by :

A

Gate Current

B

Collector current

C

Gate Voltage

D

Collector Voltage

Question 48

In Common Collector Amplifier Circuit the Output is taken from :

A

Emitter

B

Collector

C

Base

D

Both Base and Collector

Question 49

In a Cascaded Amplifier, the gain of 1^st Stage A1 is 100, Second Stage A2 is 20, third stage A3 is 10. The overall gain of :

A

100

B

130

C

20

D

20,000

Question 50

The Theoretical Efficiency of Class B Power Amplifier is :

A

50%

B

78.5%

C

70%

D

80%

Question 51

What is the First Stage of OP-Amp in Block diagram?

A

Driver

B

Push Pull Amplifier

C

Emitter Follower

D

Differential Amplifier

Question 52

The Ratio of differential Voltage gain Ad to the Common Voltage gain Acm in OP-Amp is :

A

Slew rate

B

Voltage gain

C

CMRR

D

SVRR

Question 53

In OP-Amp, Slew rate is Expressed in :

A

Seconds

B

Volts

C

Microseconds

D

Volts / Microseconds

Question 54

In IC 555, The Pin no.2 is :

A

Ground

B

Trigger

C

Output

D

Reset

Question 55

The Voltage gain of OP-Amp, as Inverting Amplifier is :

A

1+RF/R1

B

–RF × R1

C

–RF/R1

D

RF+R1

Question 56

———— are universal logic gates.

A

OR Gate and AND Gate

B

OR Gate and Ex-OR Gate

C

NAND Gate and NOR Gate

D

NOT Gate and OR Gate

Question 57

Which of the following is a Quad 2 input AND Gate?

A

7400

B

7408

C

7432

D

7486

Question 58

The logic gate that will have HIGH or 1 at its output when any one of its input is HIGH is a/an ———— gate.

A

OR

B

AND

C

NOT

D

NAND

Question 59

———— will make an AND Gate to produce a HIGH output.

A

At least one input high

B

At least one input low

C

All inputs high

D

All inputs low

Question 60

What is the use of Flip flop?

A

To store current

B

To store Binary information

C

To store voltage

D

To store analog signals

Question 61

The ability of a circuit to tolerate noise without causing unwanted changes in the output voltage is known as :

A

noise immunity

B

noise margin

C

fan-in

D

fan-out

Question 62

A full adder circuit has :

A

2 inputs and 2 outputs

B

3 inputs and 2 outputs

C

2 inputs and 3 outputs

D

None

Question 63

Which gates are ideal for checking the parity of a binary number because they produce an output 1 when the input has an odd no. of 1s?

A

OR Gate

B

AND Gate

C

EX-OR Gate

D

EX-NOR Gate

Question 64

Which circuit has 2n data inputs, one data output and n control inputs?

A

Multiplexer

B

Demultiplexer

C

Encoder

D

Decoder

Question 65

Which of the following statement is/are correct about counters?
(i) In a synchronous counter every flip flop is triggered by the clock parallel.
(ii) In an asynchronous counter the clock is applied serially.
(iii) Synchronous counters are also called as ripple counters.

A

(i) and (ii) only

B

(i) and (iii) only

C

(ii) and (iii) only

D

(i), (ii) and (iii) only

Question 66

How many inputs are available in the 7447 BCD to seven segment decoder used to drive the LED display?

A

Eight

B

Seven

C

Four

D

Two

Question 67

The logic circuits whose output at any instant of time depends not only on the present input but also on the past outputs are called :

A

Multiplexer

B

Demultiplexer

C

Combinational logic circuit

D

Sequential logic circuit

Question 68

In RS flip flop, if Q = 0 then the output is said to be :

A

current state

B

previous state

C

set

D

reset

Question 69

A shift register is defined as :

A

The register capable of shifting information to the left only

B

The register capable of shifting information to the right only

C

The register capable of shifting information either to the left or to the right

D

The register capable of shifting information to another register

Question 70

A decade counter has ———— states.

A

2

B

8

C

10

D

16

Question 71

Which circuit is used to process the demodulation of Amplitude modulated signal?

A

Ratio Detector

B

Envelope Detector

C

Slope Detector

D

Quadrature Detector

Question 72

In which modulation the signal is superimposed over the carrier waves?

A

Amplitude modulation

B

Frequency modulation

C

Phase modulatio

D

Pulse modulation

Question 73

Which type of antenna is used for point-to-point communication of radio waves?

A

Yagi antenna

B

Omni directional antenna

C

Dipole antenna

D

Parabolic antenna

Question 74

Television broadcasting is done with :

A

AM for video and audio signals

B

FM for video and audio signals

C

AM for video and FM for audio signals

D

FM for video and AM for audio signals

Question 75

Original signal can be obtained from sampled version using :

A

high pass filter

B

band pass filter

C

low pass filter

D

none of the above

Question 76

To satisfy the sampling theorem, a 200 Hz sine wave should be sampled at :

A

100 Hz

B

200 Hz

C

400 Hz

D

20 Hz

Question 77

In Frequency modulation :

A

amplitude of the carrier remains same

B

frequency of the carrier varies in accordance with the modulating signal

C

the no. of side bands are infinite

D

all of the above

Question 78

Optical fibers are highly immune to EMI. Which one of the following statement justifies it?
(i) They transmit signals as light rather than electric current.
(ii) They are shielded by outer conductors in cable.
(iii) Magnetic fields cannot penetrate through the glass of the fiber.

A

(i) only

B

(i) and (ii) only

C

All of the above

D

None

Question 79

What type of joining technique is used for fiber optic cables?

A

Soldering technique

B

Fusion technique

C

Welding technique

D

Epoxy technique

Question 80

Which light source is used for long distance and high data rate applications in fiber optic communication?

A

PIN Diode

B

Photo Diode

C

Light Emitting Diode

D

Laser Diode

Question 81

Which device is used to convert a physical quantity into its corresponding electrical signal?

A

Amplifier

B

Transducer

C

Modulator

D

Oscillator

Question 82

Which sensor detect the presence of objects without any physical contact?

A

Strain gauge

B

LVDT

C

Load cell

D

Proximity sensor

Question 83

Which device is used to convert force into electrical signal?

A

Load cell

B

Thermocouple

C

Thermister

D

LVDT

Question 84

The smallest change which a sensor can detect is known as :

A

Scale

B

Precision

C

Accuracy

D

Resolution

Question 85

RTD stands for :

A

Resistive Thermal Detector

B

Resistance Temperature Detector

C

Resistance Temperature Device

D

Resistive Thermal Device

Question 86

Which static device converts fixed DC input voltage into variable DC output?

A

Buck converter

B

Boost converter

C

DC chopper

D

AC link chopper

Question 87

Which power electronic device is used for switching purpose in computer SMPS?

A

SCR

B

IGBT

C

MOSFET

D

Transistor

Question 88

What is the advantage of on-line UPS over offline UPS?

A

It gives constant output frequency

B

It works on single phase or three phase supply

C

It gives constant power output

D

It is free from change over and transition problems

Question 89

What is the function of an Inverter?

A

Converts AC voltage into DC voltage

B

Converts AC voltage into lower AC voltage

C

Converts DC voltage into AC voltage

D

Converts AC voltage into higher AC voltage

Question 90

Which type of solar photovoltaic electric system is designed to operate in parallel and interconnected with the electric utility grid?

A

Grid tied system

B

Off-grid system

C

Specific load system

D

Higher capacity utility system

Question 91

How Many 16-Bit Registers are in 8051?

A

2

B

7

C

3

D

5

Question 92

What is bit size of 8051?

A

2

B

7

C

3

D

5

Question 93

How many Pin are there in 8051?

A

20

B

8

C

40

D

4

Question 94

How many bytes of bit addressable memory is present in 8051?

A

8

B

16

C

32

D

64

Question 95

Which is the reset pin in 8051?

A

8

B

20

C

4

D

9

Question 96

Which of the following is input devices?

A

Monitor

B

Printer

C

Keyboard

D

Speaker

Question 97

What is BIOS?

A

hardware

B

software

C

middleware

D

firmware

Question 98

Which short cut is used to Align Selected text to center?

A

Ctrl + E

B

Ctrl + C

C

Ctrl + A

D

Ctrl + L

Question 99

How Many Layers in OSI Refences Model?

A

4

B

7

C

3

D

5

Question 100

What is the Full Form of FTP?

A

File Telnet Protocol

B

File Transfer Principal

C

Follow Transfer Protocol

D

File Transfer Protocol