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120+ Electromagnetic Interference Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .

1.

Moving Iron instruments can be used on:

A. ac and dc both
B. ac only
C. dc only
D. none of the above
Answer» A. ac and dc both
2.

In spring control instruments, controlling torque:

A. can be adjusted easily
B. cannot be adjusted easily
C. remains the same
D. varies with the load
Answer» B. cannot be adjusted easily
3.

Chemical effect is used for the operation of:

A. voltmeter
B. ammeter
C. ampere hour meter
D. kwh meter
Answer» C. ampere hour meter
4.

The deflection torque can be produced by:

A. gravity control
B. spring control
C. air friction
D. magneitcally
Answer» D. magneitcally
5.

Moving coil instruments are:

A. permanent magnet type
B. dynamometer type
C. induction type
D. permanent magnet and dynamometer type
Answer» D. permanent magnet and dynamometer type
6.

For increasing the range of an ammeter, connect:

A. a high value resistance in series with the ammeter coil
B. a high value resistance in parallel with the ammeter coil
C. a low value resistance in parallel with the ammeter coil
D. a low value resistance in series with the ammeter coil
Answer» C. a low value resistance in parallel with the ammeter coil
7.

A galvanometer can be used for measuring current and voltage of a circuit by:

A. shunt only
B. connecting high value of resistance in series only
C. shunt for measuring current and high resistance in series for voltage
D. without shunt and series resistance
Answer» C. shunt for measuring current and high resistance in series for voltage
8.

The energy consumption of MI instrument as compared to MC instrument is:

A. same
B. more
C. less
D. very small
Answer» B. more
9.

An ammeter requires a change of 4A in its coil to produce a pointer deflection of 8mm then its sensitivity is

A. 2.5 mm/a
B. 2.0 mm/a
C. 0.5 mm/a
D. none of the above
Answer» B. 2.0 mm/a
10.

Electrostatic type instruments are mainly used for measurement of

A. heavy currents
B. low currents
C. low voltages
D. high voltages
Answer» D. high voltages
11.

Measurement range of a voltmeter can be extended by using:

A. high current resistance
B. high series resistance
C. low shunt resistance
D. low series resistance
Answer» B. high series resistance
12.

Which of the following voltmeter have least power consumption:

A. moving iron
B. hot-wire
C. electrostatic
D. induction type
Answer» C. electrostatic
13.

Which of the following instruments have least torque/weight ratio:

A. dynamometer type
B. pmmc
C. attraction type moving iron
D. repulsion type moving iron
Answer» A. dynamometer type
14.

Fluid friction damping can be used in

A. horizontally mounted instruments
B. vertically mounted instruments
C. both horizontally mounted instruments and vertically mounted instruments
D. none of the above
Answer» B. vertically mounted instruments
15.

The ratio and phase angle errors in potential transformer may be reduced by

A. increasing the exciting current
B. increasing the resistance and leakage reactance in the transformer
C. by not employing turns compensation
D. none of the above
Answer» D. none of the above
16.

A voltmeter should have

A. . low internal resistance
B. . high internal resistance
C. . electrostatic plates
D. . a sensitive amplifier
Answer» B. . high internal resistance
17.

The major advantage of electromagnet type meter over a permanent magnet meter is

A. . the electromagnet meter costs much less
B. the permanent magnet meter has a more sluggish coil
C. . the electromagnet meter need not be aligned with the earth’s magnetic field
D. . the electromagnet meter is more rugged
Answer» D. . the electromagnet meter is more rugged
18.

The change in the direction of a compass needle, when a current carrying wire is brought near, is called

A. . electromagnetic deflection
B. . electroscopic force
C. magnetic force
D. . electrostatic force
Answer» A. . electromagnetic deflection
19.

The use of _____ instruments is merely confined within laboratories as standardizing instruments.

A. absolute
B. indicating
C. recording
D. integrating
Answer» A. absolute
20.

Which of the following instruments indicate the instantaneous value of the electrical quantity being measured at the time at which it is being measured ?

A. absolute instruments
B. indicating instruments
C. recording instruments
D. integrating instruments
Answer» B. indicating instruments
21.

_____ instruments are those which measure the total quantity of electricity delivered in a particular time.

A. absolute
B. indicating
C. recording
D. integrating
Answer» D. integrating
22.

Which of the following are integrating instruments ?

A. ammeters
B. voltmeters
C. wattmeters
D. ampere-hour and watt-hour meters
Answer» D. ampere-hour and watt-hour meters
23.

Which of the following essential features is possessed by an indicating instrument ?

A. deflecting device
B. controlling device
C. damping device
D. all of the above
Answer» D. all of the above
24.

A _____ device prevents the oscillation of the moving system and enables the latter to reach its final position quickly

A. deflecting
B. controlling
C. damping
D. any of the above
Answer» C. damping
25.

The spring material used in a spring control device should have the following property.

A. should be non-magnetic
B. most be of low temperature co-efficient
C. should have low specific resistance
D. all of the above
Answer» D. all of the above
26.

Which of the following properties a damping oil must possess ?

A. must be a good insulator
B. should not have corrosive action upon the metal of the vane
C. the viscosity of the oil should not change with the temperature
D. all of the above
Answer» D. all of the above
27.

Which of the following devices may be used for extending the range of instruments ?

A. shunts
B. multipliers
C. current transformers
D. all of the above
Answer» D. all of the above
28.

For handling greater currents induction wattmeters are used in conjunction with

A. potential transformers
B. current transformers
C. power transformers
D. either of the above
Answer» B. current transformers
29.

The pointer of an indicating instrument should be

A. very light
B. very heavy
C. either (a) or (b)
D. neither (a) nor (b)
Answer» A. very light
30.

In majority of instruments damping is provided by

A. fluid friction
B. spring
C. eddy currents
D. all of the above
Answer» C. eddy currents
31.

An ammeter is a

A. secondary instrument
B. absolute instrument
C. recording instrument
D. integrating instrument
Answer» A. secondary instrument
32.

In a portable instrument, the controlling torque is provided by

A. spring
B. gravity
C. eddy currents
D. all of the above
Answer» A. spring
33.

The desirable static characteristics of a measuring system are

A. accuracy and reproducibility
B. accuracy, sensitivity and reproducibility
C. drift and dead zone
D. static error
Answer» B. accuracy, sensitivity and reproducibility
34.

The ratio of maximum displacement deviation to full scale deviation of the instrument is called

A. static sensitivity
B. dynamic deviation
C. linearity
D. precision or accuracy
Answer» C. linearity
35.

Systematic errors are

A. instrumental errors
B. environmental errors
C. observational errors
D. all of the above
Answer» D. all of the above
36.

The gravity controlled instrument has crowded scale because current is proportional to

A. balancing weight
B. deflection angle
C. sine of deflection angle
D. none of the above
Answer» C. sine of deflection angle
37.

Instrument transformers are

A. potential transformers
B. current transformers
C. both (a) and (b)
D. power transformers
Answer» C. both (a) and (b)
38.

The damping force acts on the moving system of an indicating instruments only when it is

A. moving
B. stationary
C. near its full scale deflection
D. just staring to move
Answer» A. moving
39.

A moving iron ammeter coil has few turns of thick wire in order to have:

A. high sensitivity
B. effective damping
C. low resistance and large current carrying capacity
D. large scale
Answer» C. low resistance and large current carrying capacity
40.

Swamping of resistance is used to compensate error due to:

A. stray magnetic field
B. temperature variations
C. large supply variations
D. none of the above
Answer» B. temperature variations
41.

The turns ratio for C.T. is defined as

A. n2/n1
B. n1/n2
C. (n1+n2)/n1
D. (n1+n2)/n2
Answer» A. n2/n1
42.

A 3810/63 P.T. is used with a voltmeter gives reading of 28.11 V , then the actual line voltage is ------ V

A. 0.4648
B. 975
C. 1700
D. 1100
Answer» C. 1700
43.

A 1000:5 C.T. is used with an ammeter. If ammeter reading is 1.8 A then the actual line current is --------------A

A. 160
B. 400
C. 0.09
D. 360
Answer» D. 360
44.

While testing cables the galvanometer used should be initially short-circuited in order to protect it from sudden initial inrush currents as the cable have:

A. a low value of initial resistance
B. a low value of initial capacitance
C. a high value of initial capacitance
D. both (a) and (b)
Answer» C. a high value of initial capacitance
45.

A megger indicates infinity when test terminals are open-circuited. This is because:

A. no current flows through the current coil
B. no current flows through the pressure coil
C. no current flows through the compensating winding
D. current does not flow through current coil and pressure coil
Answer» A. no current flows through the current coil
46.

Potentiometer is an __ instrument:

A. indicating
B. comparison
C. calibrating
D. recording
Answer» B. comparison
47.

Which of the following bridge is frequency sensitive:

A. wheatstone bridge
B. maxwell bridge
C. anderson bridge
D. wien bridge
Answer» C. anderson bridge
48.

The size of the earth or ground wire is based on the:

A. maximum fault current carrying through the ground wire
B. rated current carrying capacity of the service line
C. depends on the soil resistance
D. both (a) and (c)
Answer» D. both (a) and (c)
49.

Earth wire or ground wire is made of:

A. copper
B. aluminium
C. iron
D. galvanized steel
Answer» D. galvanized steel
50.

Average resistance of human body is:

A. 500 ohms
B. 1000 ohms
C. 1500 ohms
D. 2000 ohms
Answer» B. 1000 ohms

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