Demonstrator in Electronics and Instrumentation Answer key

Question 1

Thermocouple is an example for

A

Active transducer

B

Passive transducer

C

Photo conductive transducer

D

Photo voltatic transducer

Question 2

Residual voltage in LVDT is due to

A

Presence of Harmonics in input supply voltage

B

Presence of Harmonics in output voltage

C

Stray magnetic field

D

All of the above

Question 3

Gauge factor is highest for

A

Semiconductor strain gauge

B

Nichrome

C

Constantan

D

Foil gauge

Question 4

Piezoelectric transducer is a

A

Active transducer

B

Passive transducer

C

Inductive transducer

D

Capacitive transducer

Question 5

The change in Magnetic property of certain materials when they are mechanically stressed is known as

A

Doppler effect

B

Thomson effect

C

Coriolis effect

D

Villari effect

Question 6

Very large value of Hall effect emf is observed in

A

Metals

B

Bakelete

C

Semiconductors

D

Ceramic

Question 7

Change in resistivity due to strain is known as

A

Hall effect

B

Photo electric effect

C

Piezoelectric effect

D

None of the above

Question 8

A sensor which is able to detect the presence of nearby objects without any physical contact is called

A

Proximity sensor

B

Active sensor

C

Passive sensor

D

Smart sensor

Question 9

In a capacitive transducer the capacitance can be increased by

A

Reducing the distance of separation of parallel plates

B

Reducing the overlapping area of parallel plates

C

Reducing the dielectric constant

D

None of these

Question 10

In order to get high sensitivity a potentiometer should have

A

High input voltage

B

High value of wire length

C

Only A

D

Both A and B

Question 11

The undesirable characteristic for a strain gauge is

A

Low resistance temperature coefficient

B

Should have high hysteresis

C

Good linear characteristics

D

High frequency response

Question 12

Variable inductance transducer works on

A

Change in self inductance

B

Change of mutual inductance

C

Production of eddy currents

D

All of the above

Question 13

Which among the following is a synthetic piezoelectric material ?

A

Quartz

B

Lithium sulphate

C

Rochelle salt

D

Both B and C

Question 14

Hall effect transducer can be used for the measurement of

A

Current

B

Flow

C

Humidity

D

Capacitance

Question 15

Extremely low levels of luminous intensity can be detected using

A

Photo diodes

B

Photo transistors

C

Photomultiplier tubes

D

None of these

Question 16

Which of the following is not a unit of pressure ?

A

bar

B

psi

C

Rankine

D

Torr

Question 17

Which one of the following fluid is used in manometer ?

A

Water

B

Red oil

C

Mercury

D

All the above

Question 18

Thermal conductivity gauge used for pressure measurement is

A

McLeod gauge

B

Pirani gauge

C

Capsule gauge

D

Piezoelectric gauge

Question 19

Rapid changes of pressure can be measured using

A

Barometer

B

Piezoelectric pressure gauge

C

Bourdon tube pressure gauge

D

Diaphragm gauge

Question 20

Displacer type level detector works on

A

Pascals Law

B

Archimedes principle

C

Bernoulli’s principle

D

None of the above

Question 21

For non contact method of level measurement which one of the following is most suited ?

A

Float type level measurement

B

Displacer level measurement

C

Capacitive level measurement

D

Radiation level measurement

Question 22

Which one of the following is not a direct level measuring method ?

A

Hook-type level measuring instrument

B

Sight Glass

C

Float type indicator

D

Capacitive level measurement

Question 23

40°C = ________

A

98°F

B

110°F

C

104°F

D

108°F

Question 24

Which one of the following is suitable for non contact temperature measurement ?

A

Thermocouple

B

RTD

C

Radiation Pyrometer

D

Thermistor

Question 25

The conductor commonly used for the construction of RTD

A

Copper

B

Platinum

C

Silver

D

Aluminum

Question 26

In electromagnetic flow meters induced voltage is

A

Directly proportional to flow velocity

B

Proportional to the square of flow velocity

C

Inversely proportional to flow velocity

D

Proportional to the square root of flow velocity

Question 27

Cylinder and Piston type flow meter is a

A

Variable area flow meter

B

Magnetic flow meter

C

Differential pressure flow meter

D

Thermal flow meter

Question 28

“Stokes” is the unit of

A

Density

B

Kinematic Viscosity

C

Humidity

D

Absolute Viscosity

Question 29

Hot Wire Anemometer is used for

A

Temperature measurement

B

Humidity measurement

C

Liquid level measurement

D

Flow measurement

Question 30

Weirs are used for

A

Absolute viscosity measurement

B

Open channel flow measurement

C

Pressure measurement

D

None of the above

Question 31

Compared to open loop system closed loop systems are

A

Less sensitive to disturbances

B

Complex and Expensive

C

A and B both

D

Only A

Question 32

In force – current analogous system velocity is analogous to

A

Current

B

Voltage

C

Flux

D

Capacitance

Question 33

Product of all branch gains in a closed loop, in signal flow graph is known as

A

Path gain

B

Transmittance

C

Loop gain

D

None of the above

Question 34

The highest power of “s” in the denominator of transfer function is known as

A

Order of the system

B

Zeros of the system

C

Poles of the system

D

Type of the system

Question 35

The system response during which the output changes from one value to another value is called

A

Steady state response

B

Transient response

C

Damped response

D

None of these

Question 36

The ratio of actual damping to critical damping is called

A

Gain of the system

B

Damping ratio

C

Time constant

D

Settling time

Question 37

For a critically damped system, the damping ratio is

A

1

B

0

C

Less than 1

D

Greater than 1

Question 38

If each term of the first column of the Routh array are positive the system is

A

Unstable

B

Marginally stable

C

Stable

D

Conditionally stable

Question 39

Nichols chart can be used to determine

A

Steady state response

B

Closed loop frequency response

C

Time response

D

Open loop frequency response

Question 40

State variable approach is applicable to

A

Linear time invariant systems

B

Linear time variant systems

C

Non linear systems

D

All the above systems

Question 41

If gain margin of a system is 0 dB, then the system is

A

Stable

B

Marginally stable

C

Conditionally stable

D

Unstable

Question 42

The root locus originates from

A

Open loop zeros

B

Closed loop zeros

C

Open loop poles

D

Closed loop poles

Question 43

Alcohol is pumped through a pipe of 10 cm diameter at 4 m/s flow velocity. Find the volume flow rate.

A

0.0314 m³/s

B

1.6 m³/s

C

0.0016 m³/s

D

314 m³/s

Question 44

The standard measuring range of a sensor is 4 – 20 mA. If we have a set point value of 13 mA and a measurement of 12.5 mA, calculate the percent of span error.

A

3.125

B

– 3.125

C

2.5

D

– 2.5

Question 45

Controller with maximum stabilising time

A

P

B

PI

C

PD

D

PID

Question 46

In a proportional controller offset can be decreased by

A

Larger differential gain

B

Smaller proportional gain

C

Larger proportional gain

D

Smaller differential gain

Question 47

Which of the following statements are true regarding flashing ?

A

Valve outlet pressure is greater than the vapour pressure of the process liquid

B

Valve outlet pressure is less than or equal to the vapour pressure of the process liquid

C

Independent of vapour pressure

D

None of the above

Question 48

In air-to-close pneumatic valve, if the air supply above the diaphragm is lost, the valve will

A

fail open

B

fail close

C

either open or close

D

none of the above

Question 49

An equal percentage valve has maximum flow of 25 cm³/s and minimum of 1 cm³/s. If full travel is 2 cm, find the flow at 1 cm opening

A

12.5 cm³/s

B

5 cm³/s

C

25 cm³/s

D

50 cm³/s

Question 50

Control system which has more than one controller is

A

feedback

B

cascade

C

ratio

D

split range

Question 51

Control algorithm with one controlled output and more than one manipulated variable is

A

ratio control

B

split range control

C

cascade

D

feedback

Question 52

With increase in proportional gain speed of control system response will

A

remains the same

B

decrease

C

increases

D

oscillate

Question 53

PLC can be programmed using

A

FBD

B

Ladder logic

C

Structured text

D

All of the above

Question 54

Green colour indicates which wire type in LABVIEW ?

A

Numeral

B

Boolean

C

String

D

Hardware resource

Question 55

Which of the following is not true regarding an ideal opamp ?

A

Infinite gain

B

Infinite output impedance

C

Null voltage offset

D

None of the above

Question 56

Symbol for continuous pneumatic symbol in P and I diagram.

A

A)

B

B)

C

C)

D

D)

Question 57

Symbol of gate valve is

A

A)

B

B)

C

C)

D

D)

Question 58

A telemetry system using synchro transmitter and receiver is an example of

A

voltage telemetry system

B

current telemetry system

C

position telemetry system

D

radio frequency telemetering systems

Question 59

Which of the following is not true about landline telemetry system ?

A

is free from transmission link distortions

B

the effects of thermo-electric emfs are substantial

C

the frequency response is limited

D

signal multiplexing tends to be impracticable

Question 60

In long distance telemetry data is transmitted in form of

A

current

B

voltage

C

position

D

frequency

Question 61

End devices at telemetry receiver cannot be

A

detector

B

recorder

C

display

D

controller

Question 62

Force balance system is a type of

A

position telemetry system

B

current telemetry system

C

voltage telemetering systems

D

radio frequency telemetering systems

Question 63

Beer-Lambert’s law holds good only for

A

white light

B

dichromatic light

C

polychromatic light

D

monochromatic light

Question 64

In a paramagnetic oxygen analyser highest point for which dry air is used to set the span point.

A

21 percent

B

25 percent

C

12 percent

D

28.8 percent

Question 65

The material that cannot be used for construction of filament in hot wire thermal conductivity analyser is

A

Tungsten

B

Magnanin

C

Kovar

D

Platinum

Question 66

Which of the following is a classification of liquid chromatography ?

A

Paper chromatography

B

Column chromatography

C

Thin layer chromatography

D

All of the above

Question 67

_________ is known as heart of a gas chromatograph, where the fundamental process of separation takes place.

A

Injection system

B

Column

C

Thermal compartment

D

Platinum

Question 68

Ions of different m/e ratio are separated by the difference in time they take to travel over an identical path from the ion source to the collector. This is the working principle of

A

Magnetic deflection mass spectrometer

B

Time-of-flight mass spectrometer

C

NMR spectrometer

D

Raman effect spectro photometer

Question 69

In which part of the flame photometer aerosol is produced and fed into the flame

A

Burner

B

Atomiser

C

Flame

D

Regulator

Question 70

Reference electrode that is used at high temperatures in pH measurement

A

Ag/ AgCl electrode

B

Mercury/ mercurous electrode

C

Hydrogen electrode

D

Glass electrode

Question 71

If identical solutions are placed inside and outside the bulb of the glass electrode, it is found that in spite of the apparent symmetry of the cell so formed, there exists an emf of a few millivolt. This potential difference is called the

A

Asymmetry potential

B

Symmetry potential

C

Acid error

D

Alkali error

Question 72

Detector used in infrared spectrophotometer when a response time of 0.5 ms is required

A

Photoconductive cell

B

Golay cell

C

Thermocouple

D

Bolometer

Question 73

In ECG waveform _________ wave represents repolarisation of both ventricles.

A

QRS complex

B

P wave

C

T wave

D

U wave

Question 74

In EEG m/m number of electrode locations in the 10/20 system is

A

24

B

15

C

5

D

21

Question 75

__________ is not a part of emg machine.

A

Amplifier

B

CRO

C

Montage selector

D

Loud speaker

Question 76

Natural pacemaker of heart is

A

Sinoatrial node

B

Atrioventricular node

C

Bundle of HIS

D

Purkinje fibre

Question 77

The magnitude of the voltage picked up in an electromagnetic blood flow meter is not directly proportional to the

A

strength of the magnetic field

B

the diameter of the blood vessel

C

the velocity of blood flow

D

polarity of magnetic field

Question 78

The electrical shock that reaches to the heart directly and is highly concentrated is called

A

Micro shock

B

Macro shock

C

Extracorporeal shock

D

Cardiogenic shock

Question 79

Process of changing from resting potential to action potential is known as

A

Repolarisation

B

Depolarisation

C

Polarisation

D

Sodium pump

Question 80

In CT scanners the impact of an X-ray photon with an electron is accompanied by a transfer of energy and a fall in the X-ray frequency. This is known as

A

Compton effect

B

Planks effect

C

Newton effect

D

Einsteen effect

Question 81

Which phenomenon causes polarization of light ?

A

Total internal reflection

B

Interference

C

Double refraction

D

None of these

Question 82

In a Newton’s ring experiment, diameter of 10^th dark ring due to a wavelength of 500 nm in water (μ = 1.5) is 5 mm. The radius of curvature of lens is

A

157 cm

B

187 cm

C

193 cm

D

167 cm

Question 83

Match the following :

i. Photodiode	a. High sensitivity
ii. PIN diode	b. Microwave switch
iii. Avalanche photodiode	c. Low output response
iv. LED	d. Fast output response
v. Phototransistor

A

i-c, ii-b, iv-a, v-d

B

i-d, ii-b, iii-a, v-c

C

i-d, iii-a, iv-c, v-b

D

None of these

Question 84

Which of the following is true about Numerical Aperture (NA) ?
i. NA determines the light gathering ability of fibre
ii. It depends only on the refractive indices of core and cladding
iii. It’s value ranges from 0.5 to 1
iv. It is defined as sine of critical angle

A

Only i, ii and iv are true

B

Only i, ii and iii are true

C

Only i and ii are true

D

All the above are true

Question 85

Match the following :

i. Ruby Laser	a. T.H. Maiman
ii. Argon Laser	b. 2 level laser
iii. He-Ne Laser	c. ion laser
iv. Semiconductor laser	d. 632.8 nm

A

i-a, ii-c, iii-b, iv-d

B

i-d, ii-a, iii-c, iv-b

C

i-a, ii-c, iii-d, iv-b

D

None of these

Question 86

Which of the following is true ?
i. Oscilloscope is basically a voltmeter
ii. CRO is a fast x-y plotter
iii. Effect of negative voltage to the grid is an attractive force
iv. Focusing and accelerating anodes are cylindrical
v. During flyback period, voltage is very high

A

All are true

B

Only i, ii and iv are true

C

Only i and ii are true

D

Only i and iv are true

Question 87

The inductance of a moving iron instrument is given by : L = (40 + 2θ – θ2)μH, where θ is the deflection in radians from zero position. The spring constant is 12 x10–6 Nm/rad. Estimate the deflection for a current of 2A.

A

0.5 rad

B

0.25 rad

C

0.15 rad

D

0.75 rad

Question 88

A simple equal arm voltage sensitive bridge is initially balanced. Three of the arms consists of ordinary resistors, while the fourth is a thermistor. Each arm has a nominal resistance of 1KΩ and the bridge is energised with a 10V dc source. If a temperature change causes a + 15% change in thermistor resistance, what output voltage (approximately) will be indicated from the bridge ?

A

349 mV

B

35 mV

C

215 mV

D

None of these

Question 89

Which of the following is true ?
i. An ammeter is used for measuring magnitude and direction of current flow
ii. D’ Arsonval galvanometer is used to measure small voltage and current in the circuit
iii. Galvanometer connected with high resistance in series is used as ammeter
iv. A galvanometer also is known as PMMC instrument

A

Only i, ii and iv are true

B

Only i and iv are true

C

Only ii, iii and iv are true

D

Only ii and iv are true

Question 90

The two-wattmeter method is used to measure power in a balanced 3-phase circuit, drawing lagging current. The power factor if one of the wattmeters reads twice the value of the other wattmeter.

A

1/√2

B

1

C

1/2

D

√3/2

Question 91

A (0-120)V voltmeter has an accuracy of 1% full scale reading. The voltage is 60 V. The limiting error is

A

2%

B

0.2%

C

1.2%

D

None of these

Question 92

An ammeter has a current range of 0 – 10A, and its internal resistance is 0.5Ω. In order to change the range to 0 – 50A, we need to add a resistance of

A

0.125 Ω in parallel with the meter

B

0.125 Ω in series with the meter

C

0.1 Ω in parallel with the meter

D

0.1 Ω in series with the meter

Question 93

A stationary closed Lissajous pattern on an oscilloscope has 5 horizontal tangencies and 3 vertical tangencies for a vertical input with frequency 8 kHz. The frequency of horizontal input is

A

4.8 kHz

B

13.3 kHz

C

8 kHz

D

1 kHz

Question 94

An amplifier has an open loop voltage gain of – 300. This gain is reduced to – 100 when negative feedback is applied. The reverse transmission factor β of this system is

A

– 0.0033

B

– 0.0066

C

0.0033

D

0.0066

Question 95

Match the following :

i. SCR	a. bidirectional switch
ii. Transistor	b. switch
iii. TRIAC	c. bidirectional uncontrolled device
iv. DIAC	d. switch and amplifier

A

i-a, ii-b, iii-d, iv-c

B

i-b, ii-d, iii-a, iv-c

C

i-b, ii-d, iii-c, iv-a

D

i-d, ii-b, iii-c, iv-a

Question 96

Simplify the expression :

A

A)

B

B)

C

C)

D

C)

Question 97

Two passive RC integrator circuits are connected in series. If the input to the first RC integrator circuit is a pulse waveform, what will be the output of secondary RC integrator circuit ?

A

Triangular wave

B

Spikes

C

Sine wave

D

Square wave

Question 98

The number of special function registers in 8051 is

A

20

B

21

C

22

D

23

Question 99

Consider the following program. Let’s assume that internal memory 80 H contains 05 H.
ORG00H
MOV R3, #80H
MOV A, @R3
MOV B, A
ADD A, B
END
Choose the right answer.

A

Accumulator will contain 10H

B

Accumulator will contain 0AH

C

Syntax error

D

Not able to access internal memory

Question 100

Example of a register addressing mode is
i. MOV A, B
ii. MOV R1, R0
iii. MOV A, @R1
iv. MOV B, R3

A

Only ii and iv

B

Only i, ii and iv

C

Only i and iv

D

All i, ii, iii and iv

129/2022 - Demonstrator in Electronics and Instrumentation & Instrument Technology