Olete.in – MCQs, Mock Tests & Government Job Prep | Electrical measurements Electrical Measurement MCQ Question Set 2

Why a Wheatstone bridge can’t be used for signal conditioning?

1. due to the galvanometer
2. due to excessive current flow
3. due to the e.m.f source used
4. due to lead wires

✅ Correct Answer: 4

How to minimize the drift in the value of resistance measured using a Wheatstone bridge?

1. by using a high precision null detector
2. by keeping the lead wire resistances within 0.2 mΩ
3. by using a e.m.f source of minimum value
4. by minimizing the flow of current

✅ Correct Answer: 2

Low resistance refers to _____

1. resistances of the order of 1ῼ
2. resistances of the order of 1kῼ
3. resistances of the order of 1mῼ
4. resistances of the order of 1Mῼ

✅ Correct Answer: 1

What is the significance of measuring low resistances?

1. voltage drop across the circuit is high
2. contact and lead resistances are appreciable
3. there is no power loss
4. no current flows through the bridge circuit

✅ Correct Answer: 2

How is the voltage drop across a low resistance related to lead resistance?

1. it contains contact resistance
2. it depends on the magnitude of voltage drop
3. it depends on the type of null detector used
4. It does not contain any contact resistance

✅ Correct Answer: 4

Which is not a source of error in the measurement of low resistance?

1. contact resistance drops at the leads
2. thermal e.m.f
3. temperature effect
4. power dissipation through the circuit

✅ Correct Answer: 1

Which is the most popular method for measuring low resistance?

1. ammeter-voltmeter method
2. potentiometer method
3. kelvin double bridge method
4. ducter ohmmeter method

✅ Correct Answer: 3

How is the contact resistance related to the circuit while measuring a low resistance?

1. independent of the type of resistance
2. it is negligible
3. depends on the e.m.f source
4. it is very high

✅ Correct Answer: 2

Kelvin’s bridge consists of _______

1. double bridge
2. single bridge
3. half bridge
4. three fourth bridge

✅ Correct Answer: 1

The range of resistance measured in a Kelvin bridge is _____

1. 10Ω to 10 mΩ
2. 1Ω to 10 μΩ
3. 0.01Ω to 10 MΩ
4. 0.1Ω to 10 nΩ

✅ Correct Answer: 2

Accuracy of Kelvin bridge is of the order of _______

1. ±0.5 to ±2 %
2. ±0.05 to ±0.02 %
3. ±0.05 to ±0.2 %
4. ±0.005 to ±0.02 %

✅ Correct Answer: 3

What is the effect of load and contact resistance in Kelvin bridge?

1. independent
2. fully dependent
3. partially dependent
4. depends on the resistance value

✅ Correct Answer: 1

The relation between ratio of resistance arms and ratio of resistance arms of second bridge is ____

1. unequal
2. equal
3. twice
4. one forth

✅ Correct Answer: 2

Why Kelvin bridge is used for measurement of low resistance?

1. due to e.m.f source used
2. due to a large current flow
3. due to contact and lead resistance
4. due to power dissipation across the circuit

✅ Correct Answer: 3

What is the condition to achieve a high sensitivity in a Kelvin bridge?

1. low voltage
2. high power
3. medium resistance
4. high current

✅ Correct Answer: 4

Kelvin bridge can be calibrated to read ____

1. inductance and Quality factor value
2. capacitance only
3. power and voltage
4. current and frequency

✅ Correct Answer: 1

Why can’t a Kelvin bridge be used for the measurement of low Quality factor value?

1. due to thermoelectric effect
2. due to balance problem
3. due to the dull detector used
4. due to temperature

✅ Correct Answer: 2

High resistances are of the order of _____

1. 0.1 Mῼ
2. 10 mῼ
3. 1 kῼ
4. 10 Gῼ

✅ Correct Answer: 1

Megger is a ________

1. source of e.m.f
2. source to measure high resistance
3. type of a null detector
4. current carrier

✅ Correct Answer: 2

Megger is also used for _____

1. providing additional e.m.f
2. bridge balance
3. testing insulation resistance
4. controlling the temperature

✅ Correct Answer: 3

Megger works on the principle of ______

1. kirchhoff’s current laws
2. ohm’s law
3. gauss’s law
4. electromagnetic induction

✅ Correct Answer: 4

The role of the permanent magnet in a megger is to ________

1. provide field
2. provide voltage
3. generate power
4. balance the circuit

✅ Correct Answer: 1

A guard ring is provided in a megger to ________

1. protect the circuit
2. eliminate error
3. reduce current flow
4. limit the temperature rise

✅ Correct Answer: 2

The supply to the megger is given by ________

1. ac motor
2. ac generator
3. permanent magnet dc motor
4. dc generator

✅ Correct Answer: 3

The moving element of the ohmmeter in a megger consists of ______

1. 1 coil
2. 4 coils
3. 3 coils
4. 10 coils

✅ Correct Answer: 3

The role of the compensating coil in a megger is ________

1. reduce current
2. increase voltage
3. control temperature
4. scaling

✅ Correct Answer: 4

Why is the scale of a megger calibrated in megaohms?

1. to indicate resistance
2. to minimise the current flow
3. to increase the voltage drop
4. to reduce the temperature

✅ Correct Answer: 1

Megger can be used for verifying the electrical insulation level of _______

1. passive components such as resistance, capacitor and inductance
2. devices such as motor, cable, etc
3. solid state devices
4. liquid crystal devices

✅ Correct Answer: 2

Continuity between any two points can be measured using ______

1. ammeter
2. voltmeter
3. megger
4. galvanometer

✅ Correct Answer: 3

Electrical continuity between any two points exists if ______

1. there is current flow through them
2. there is a wire connecting the points
3. there is sufficient voltage drop
4. pointer shows deflection

✅ Correct Answer: 4

Megger is also known as _____

1. megohmmeter
2. multimeter
3. galvanometer
4. ammeter

✅ Correct Answer: 1

The application of a megger is _____

1. to measure resistance
2. to test for leakage
3. to limit the current
4. to increase the emf of the circuit

✅ Correct Answer: 2

What is the significance of a megger with respect to high resistance?

1. it is used to limit the current
2. it is used to provide stability
3. used for measuring high resistance with respect to ground
4. it is used for temperature protection

✅ Correct Answer: 3

How is the megger calibrated?

1. in steps of 1 unit per division
2. based on the value of resistance to be measured
3. directly calibrated on the position of the pointer
4. reversely calibrated based on the pointer position

✅ Correct Answer: 4

What is earthing?

1. connecting electrical machines to earth
2. providing a connection to the ground
3. connecting the electrical machines to source
4. providing a source of current

✅ Correct Answer: 1

What is an earth electrode?

1. electrode that is connected to earth
2. material used for earthing
3. electrode connected to the circuit
4. electrode which is connected to the mains

✅ Correct Answer: 2

Earth electrode provides _____

1. high resistance
2. medium resistance
3. low resistance
4. very high resistance

✅ Correct Answer: 3

How is the condition of an earth electrode measured?

1. by measuring the voltage
2. by measuring the current
3. by measuring the power
4. by measuring resistance

✅ Correct Answer: 4

In a three phase system, the neutral is ____

1. earthed
2. connected to low voltage
3. connected to high voltage
4. not connected

✅ Correct Answer: 1

Earthing is used as return conductor in telephone lines and for traction work.

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

✅ Correct Answer: 1

Earthing does not help in protecting the equipment.

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

✅ Correct Answer: 2

After earthing, the different parts of an electrical machinery are at _____

1. infinite potential
2. intermediate potential
3. zero potential
4. undefined potential

✅ Correct Answer: 3

Connection of the various parts of a circuit to earth has a ______

1. medium resistance
2. high resistance
3. very high resistance
4. very low resistance

✅ Correct Answer: 4

Specific resistance of soil is _______

1. changes from soil to soil
2. is constant
3. depends on the circuit connected to it
4. depends on the supply voltage

✅ Correct Answer: 1

The readings of polar type potentiometer are I = 12.4∠27.5°, V = 31.5∠38.4°. Then, reactance of the coil will be ______

1. 2.51 Ω
2. 2.56 Ω
3. 2.54 Ω
4. 2.59 Ω

✅ Correct Answer: 3

The voltage drop across a standard resistor of 0.2 Ω is balanced at 83 cm. Find the magnitude of the current, if the standard cell emf of 1.53 V is balanced at 42 m.

1. 13.04 A
2. 10 A
3. 14.95 A
4. 12.56 A

✅ Correct Answer: 3

Low resistance is measured by _______

1. De-Sauty’s bridge
2. Maxwell’s bridge
3. Kelvin double bridge
4. Wein’s bridge

✅ Correct Answer: 3

The resistance can be measured most accurately by _______

1. Voltmeter-Ammeter method
2. Bridge method
3. Multimeter
4. Megger

✅ Correct Answer: 2

A slide wire potentiometer has 10 wires of 2 m each. With the help of a standard voltage source of 1.045 V, it is standardized by keeping the jockey at 104.5 cm. If the resistance of potentiometer wires is 2000 Ω, then the value of working current is?

1. 1 mA
2. 10 mA
3. 0.1 mA
4. 0.5 mA

✅ Correct Answer: 2

A resistor of 10 kΩ with the tolerance of 5% is connected in parallel with 5 kΩ resistors of 10% tolerance. What is the tolerance limit for a parallel network?

1. 9%
2. 12.4%
3. 8.33%
4. 7.87%

✅ Correct Answer: 3