Electrical Measurements and Instrumentation Questions & Answers

Electrical Measurements and Instrumentation Objective Questions & Answers

[1] A 10MHz CRO has

(a) 5MHz sweep
(b) 10MHz vertical oscillator
(c) 10MHz horizontal oscillator
(d) 10MHz supply frequency

[2] Which of the following instruments can be used to measure AC current only?

(a) Permanent Magnet Type ammeter
(b) Induction type ammeter
(c) Moving iron voltmeter
(d) Moving iron ammeter

choose the right Answer:

D only
B only
A, B, D
B and D only

[3] An oscilloscope indicates

(a) Peak to peak value of voltage
(b) DC value of voltage
(c) RMS value
(d) Average value

[4] In a ballistic galvanometer, the deflecting torque is proportional to

(a) the current through coil
(b) square of current through coil
(c) square-root of current through coil
(d) sine of measured

[5] The error of an instrument is normally given as a percentage of

(a) measured value
(b) full-scale value
(c) mean value
(d) rms value

[6] If the instrument is to have a wide range, the instrument should have

(a) Linear scale
(b) Square-law scale
(c) Exponential scale
(d) Logarithmic scale

[7] The resistance can be measured most accurately by

(a) Voltmeter-ammeter method
(b) bridge method
(c) multimeter
(d) Megger

[8] The repeat accuracy of an instrument can be judged from its

(a) static error
(b) linearity error
(c) dynamic error
(d) standard deviation of error

[9] Which of the following meters has a linear scale?

(a) Thermocouple meter
(b) Moving iron meter
(c) Hot wore meter
(d) Moving coil meter

[10] No eddy current and hysteresis losses occur in

(a) Electrostatic instruments
(b) PMMC instruments
(c) Moving iron instruments
(d) Electrodynamo meter instruments

[11] Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are

(a) 360V and 240V
(b) 300V each
(c) 400V and 200V
(d) one of the meters out of the range and other 100V

[12] The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100Ohm. If this meter is to have full deflection at 5A, what is the value of the shunt resistance to be used?

(a) 49.99 Ohms
(b) 1/49.99 ohms
(c) 1 Ohm
(d) 2 Ohms

[13] The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100Ohm. This is to have full deflection when 100V is measured. What is the value of series resistor to be used?

(a) 99.99 K ohms
(b) 100 K ohms
(c) 99.99 ohms
(d) 100 ohms

[14] Why is a MISC meter not recommended for DC measurement?

(a) The meter is calibrated for AC and it’s error for DC would be high
(b) The meter does not respond to DC signals
(c) The error is high due to hysteresis effect
(d) The error is high due to eddy current effect

[15] The EMF of Weston standard cell is measured using

(a) Moving- iron meter
(b) Moving-coil meter
(c) Digital Volt meter
(d) Potentiometer

ANSWERS

[1] A 10MHz CRO has

Ans: C

[2] Which of the following instruments can be used to measure AC current only?

Ans: 2

[3] An oscilloscope indicates

Ans: A

[4] In a ballistic galvanometer, the deflecting torque is proportional to

Ans:A

[5] The error of an instrument is normally given as a percentage of

Ans: B

[6] If the instrument is to have a wide range, the instrument should have

Ans:D

[7] The resistance can be measured most accurately by

Ans: B

[8] The repeat accuracy of an instrument can be judged from its

Ans: D

[9] Which of the following meters has a linear scale?

Ans: D

[10] No eddy current and hysteresis losses occur in

Ans: A

[11] Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are

Ans: A

Ans: B

Ans: A

[14] Why is a MISC meter not recommended for DC measurement?

Ans: C

[15] The EMF of Weston standard cell is measured using

Ans: D

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