Olete.in – MCQs, Mock Tests & Government Job Prep | Electrical measurements Electrical Measurement MCQ Question Set 3

Ra and Rd are the opposite arms of a Wheatstone bridge as are Rc and Rb. The source voltage is applied across Ra and Rc. Then when the bridge is balanced which one of the following is true?

1. Ra = Rc Rd/Rb
2. Ra = Rc Rd/Rb
3. Ra = Rb Rd/Rc
4. Ra = Rb + Rc + Rd

✅ Correct Answer: 2

A setup is used to measure resistance R. The ammeter and voltmeter resistance are 0.01 Ω and 2000 Ω respectively. Their readings are 2 A and 180 V respectively, giving a measured resistance of 90 Ω. The percentage error in the measurement is?

1. 2.25 %
2. 2.35 %
3. 4.5 %
4. 4.71 %

✅ Correct Answer: 4

A 35 V DC supply is connected across a resistance in series with an unknown resistance R. a voltmeter having a resistance of 1.2 kΩ is connected across 600 Ω resistance and reads 5 V. The value of the known resistance is 600 Ω. The value of resistance R will be?

1. 120 Ω
2. 400 Ω
3. 1.8 kΩ
4. 2.4 kΩ

✅ Correct Answer: 4

A DC ammeter is rated for 15 A, 250 V. The meter constant is 14.4 A-s/rev. The meter constant at rated voltage may be expressed as ______

1. 3750 rev/kW-h
2. 3600 rev/kW-h
3. 1000 rev/kW-h
4. 960 rev/kW-h

✅ Correct Answer: 3

A DC ammeter has a resistance of 0.1 Ω and its current range is 0-100 A. If the range is to be extended to 0-500 A, the meter requires which of the following shunt resistance?

1. 0.010 Ω
2. 0.011 Ω
3. 0.025 Ω
4. 1.0 Ω

✅ Correct Answer: 3

A 100 μA ammeter has an internal resistance of 100 Ω. The range is to be extended to 500 μA. The shunt required is of resistance ______

1. 20.0 Ω
2. 22.22 Ω
3. 25.0 Ω
4. 50.0 Ω

✅ Correct Answer: 3

Resistance is measured by the voltmeter-ammeter method employing DC excitation and a voltmeter is connected directly across the unknown resistance. If the voltmeter and ammeter readings are subject to maximum possible errors of ±2.4 % and ±1% respectively, then the magnitude of the maximum possible percentage error in the value of resistance deduced from the measurement is?

1. 1.4 %
2. 1.7 %
3. 2.4 %
4. 3.4 %

✅ Correct Answer: 4

A galvanometer with a full-scale current of 10 mA has a resistance of 1000 Ω. The multiplying power of a 100 Ω shunt with this galvanometer is?

1. 110
2. 100
3. 11
4. 10

✅ Correct Answer: 3

The simultaneous applications of signals x (t) and y (t) to the horizontal and vertical plates respectively, of an oscilloscope, produce a vertical figure of 8 displays. If P and Q are constants and x(t) = P sin (4t + 30), then y(t) is equal to _____

1. Q sin (4t -30)
2. Q sin (2t +15)
3. Q sin (8t +60)
4. Q sin (4t +30)

✅ Correct Answer: 2

In the simplest form, an AC bridge consists of _______

1. arms, source and a detector
2. arms and source
3. source and detector
4. arms and detector

✅ Correct Answer: 1

Source is _______

1. dc supply
2. ac supply
3. mixed mode supply
4. high voltage supply

✅ Correct Answer: 2

At high frequency, source consists of ______

1. amplifiers
2. regulators
3. oscillators
4. op amps

✅ Correct Answer: 3

What is the frequency range for a headphone as a detector?

1. 20 Hz to 20 kHz
2. 10 kHz to 1 MHz
3. 10 MHz to 1 GHz
4. 250 Hz to 4 kHz

✅ Correct Answer: 4

For single frequency value, the most sensitive detector is ____

1. tuned detector
2. vibration galvanometer
3. headphone
4. oscillator

✅ Correct Answer: 1

Tuned detectors are used in the frequency range of ____

1. 1 Hz to 100 Hz
2. 10 Hz to 100 Hz
3. 1 kHz to 100 kHz
4. 1 MHz to 100 MHz

✅ Correct Answer: 2

Vibration galvanometers are used for ____

1. very high frequency
2. very low frequency
3. low audio frequency
4. high audio frequency

✅ Correct Answer: 3

AC bridge is an outcome of ________

1. Kelvin bridge
2. Megger
3. De Sauty bridge
4. Wheatstone bridge

✅ Correct Answer: 4

At very low frequencies in a AC bridge, the source is ______

1. power line
2. e.m.f
3. galvanometer
4. tuned circuit

✅ Correct Answer: 1

At high frequencies in an AC bridge, the source is _______

1. tuned amplifiers
2. oscillators
3. vibration galvanometer
4. high voltage source

✅ Correct Answer: 2

The frequency range of a typical oscillator is _______

1. 1 Hz to 50 Hz
2. 1 kHz to 100 KHz
3. 40 Hz to 125 kHz
4. 1 MHz to 150 MHz

✅ Correct Answer: 3

The power output for a typical oscillator is _____

1. 1 kW
2. 1 MW
3. 1 mW
4. 7 W

✅ Correct Answer: 4

The output waveform in an oscillator is _______

1. sinusoidal
2. cosinusoidal
3. tangential
4. logarithmic

✅ Correct Answer: 1

The output frequency of an oscillator is _______

1. unstable and fixed
2. stable and adjustable
3. stable and fixed
4. unstable and variable

✅ Correct Answer: 2

The output power of an oscillator is not enough to drive power circuits.

1. True
2. False
3. all of the above
4. None of the mentioned

✅ Correct Answer: 2

Tuned amplifiers can be set to _______

1. low frequencies
2. high frequencies
3. any frequency
4. audio frequencies

✅ Correct Answer: 3

Tuned amplifier circuits respond to broad bandwidth at bridge frequency.

1. True
2. False
3. all of the above
4. None of the mentioned

✅ Correct Answer: 2

Bridge balance equation for magnitude is given by which of the following relation?

1. Z1 Z4 = Z2 Z3
2. Z1 Z2 = Z3 Z4
3. Z2 Z4 = Z1 Z3
4. Z1 Z3 = Z2 Z4

✅ Correct Answer: 1

Bridge must be balanced for _____

1. magnitude
2. angle
3. magnitude and angle
4. power

✅ Correct Answer: 3

Phase angle is based on _______

1. source
2. detector
3. power
4. impedance

✅ Correct Answer: 4

For inductive impedances, the phase angle is _______

1. positive
2. negative
3. zero
4. exponential

✅ Correct Answer: 1

For capacitive impedances, the phase angle is _______

1. tangential
2. negative
3. positive
4. logarithmic

✅ Correct Answer: 2

Bridge balance equation for magnitude in terms of admittances is given by the relation.

1. Y1Y3 = Y2Y4
2. Y1Y2 = Y3Y4
3. Y1Y4 = Y2Y3
4. Y1 Y3 = Y2 Y4

✅ Correct Answer: 3

When a bridge is balanced?

1. no voltage drop across the circuit
2. power dissipation is high
3. temperature of the circuit is high
4. no current flows

✅ Correct Answer: 4

In a capacitance bridge, the arms are _________

1. resistive
2. capacitive
3. inductive
4. mixture of resistance, capacitance and inductance

✅ Correct Answer: 1

How is the bridge balanced?

1. using resistance R1
2. using resistance R1
3. through capacitance C3
4. through capacitance Cx

✅ Correct Answer: 2

Impedance Z4 consists of ______

1. resistance Rx
2. capacitance Cx
3. combination of capacitance Cx and resistance Rx
4. consists of a detector

✅ Correct Answer: 3

Impedance Z3 consists of______

1. resistance R3
2. capacitance C3
3. vibration galvanometer
4. capacitance C3 in series with resistance R3

✅ Correct Answer: 4

Unknown capacitance value is obtained by ______

1. comparison with standard
2. using a tuned detector
3. using capacitance of other ratio arms
4. using a vibration galvanometer

✅ Correct Answer: 1

Actual balance condition can be obtained by _____

1. varying R1
2. varying R3
3. varying R2
4. varying R1 and R3

✅ Correct Answer: 4

Inductance comparison bridge is used to compute _____

1. unknown inductance and resistance
2. unknown resistance
3. unknown inductance
4. unknown capacitance

✅ Correct Answer: 1

Ratio arms of the bridge consists of _____

1. pure inductances
2. pure resistances
3. pure capacitances
4. inductance and capacitance

✅ Correct Answer: 2

Inductance control is obtained by ______

1. using R2
2. using R1
3. using R1
4. using Lx

✅ Correct Answer: 1

Bridge depends on frequency.

1. True
2. False
3. all of the above
4. None of the mentioned

✅ Correct Answer: 2

Bridge can be used at audio frequency.

1. True
2. False
3. all of the above
4. None of the mentioned

✅ Correct Answer: 2

Bridge is used for the measurement of _________

1. high Q factor
2. medium Q factor
3. low Q factor
4. very low Q factor

✅ Correct Answer: 2

Anderson bridge is used for ________

1. the measurement of self-inductance
2. the measurement of resistance
3. the measurement of capacitance
4. the measurement of impedance

✅ Correct Answer: 1

Anderson bridge is a modified form of ________

1. Wheatstone’s bridge
2. Maxwell bridge
3. Kelvin double bridge
4. Schering bridge

✅ Correct Answer: 2

Anderson’s bridge is basically used for ________

1. measurement of capacitance
2. measurement of resistance
3. measurement of inductance
4. measurement of voltage

✅ Correct Answer: 3

Balance equation for computing the inductance is ________

1. Lx = R3 R5
2. Lx = CR5
3. Lx = CR3
4. Lx = CR3 R5

✅ Correct Answer: 4

When the capacitor used is imperfect, the inductance value changes.

1. True
2. False
3. all of the above
4. None of the mentioned

✅ Correct Answer: 2