Question 1

Generally grounding is provided for:
A)only for the safety of the equipment
B)only for the safety of the operating personnel
C)both (a) and (b)
D)none of the above

Accepted Answer

Grounding is provided for both the safety of the equipment and the safety of the operating personnel. It helps in protecting against electrical overloads and ensures that in the event of a fault, the electrical current has a safe path to the ground, reducing the risk of electric shock or fire.

Question 2

Ground resistance should be designed such that:
A)grounding resistance should be as low as possible
B)grounding resistance should be as high as possible
C)grounding resistance should be always zero
D)none of the above

Accepted Answer

Grounding resistance should be as low as possible to ensure that in the event of a fault, the electrical current can be safely diverted to the ground, minimizing the risk of electric shock or fire.

Question 3

The objective of earthing or grounding is:
A)to provide as low resistance possible to the ground
B)to provide as high resistance possible to the ground
C)to provide flow of positive, negative and zero sequence currents
D)none of the above

Accepted Answer

The objective of earthing or grounding is to provide as low a resistance path as possible to the ground. This ensures that in the event of a fault, electrical current can safely dissipate into the earth, reducing the risk of electric shock or fire.

Question 4

The vale of resistance of an earthing electrode depends upon
A)shape and material of the electrode
B)depth to which electrode is driven into earth
C)specific resistance of soil
D)all of the above.

Accepted Answer

The value of resistance of an earthing electrode is influenced by the shape and material of the electrode, the depth to which the electrode is driven into the earth, and the specific resistance of the soil. All these factors collectively determine the overall resistance.

Question 5

A bridge circuit works at a frequency of 2KHz, the following can be used as detectors for detection of null conditions in the bridge:
A)vibration galvanometers and headphones
B)headphones and tunable amplifiers.
C)vibration galvanometers and tunable amplifiers.
D)vibration galvanometers, headphones and tunable amplifiers.

Accepted Answer

The answer of A bridge circuit works at a frequency...

Question 6

Maxwell's inductance capacitance bridge is used for measurement of inductance of:
A)low q coils
B)medium q coils
C)low and medium q coils
D)none of the above.

Accepted Answer

The answer of Maxwell's inductance capacitance bridge is used for...

Question 7

The wheatstone bridge cant be used for precision measurements because errors are introduce into on account of :
A)resistance of connecting leads
B)thermo electric emf
C)contact resistances
D)all of the above.

Accepted Answer

The Wheatstone bridge can introduce errors in precision measurements due to the resistance of connecting leads, thermo-electric EMF, and contact resistances. These factors can affect the accuracy of the measurements by introducing additional unwanted resistances and voltages.

Question 8

High resistances are provided with a guard terminal. This guard terminal is used to :
A)bypass leakage current
B)guard the resistance against stray electrostatic fields
C)guard the resistance against over loads.
D)none of the above.

Accepted Answer

The guard terminal is used to bypass leakage current, preventing it from affecting the measurement of high resistance values.

Question 9

A potentiometer may be used for
A)measurement of resistance
B)measurement of current
C)calibration of voltmeter
D)all of the above

Accepted Answer

A potentiometer is a versatile instrument that can be used for various purposes including the measurement of resistance, measurement of current, and calibration of voltmeters. This is because it measures voltage as a function of slider position on a uniform resistance, allowing for precise control and measurement of electrical parameters.

Question 10

--------- is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another,
A)tangent galvanometer
B)meggar
C)current transformer
D)none of the above

Accepted Answer

A megger is specifically designed to measure the insulation resistance of electrical circuits relative to the earth and to each other, which is crucial for ensuring the safety and efficiency of electrical installations.

Question 11

For measuring a very high resistance we should use
A)kelvin\s double bridge
B)wheat stone bridge
C)meggar
D)none of the above

Accepted Answer

Meggar is specifically designed for measuring very high resistances, often in the range of megaohms, which is ideal for testing insulation resistance in electrical installations. Kelvin's double bridge and Wheatstone bridge are more suited for measuring low to moderate resistances accurately.

Question 12

The electrical power to a meggar is provided by
A)battery
B)permanent magnet d.c. generator
C)ac. generator
D)any of the above

Accepted Answer

A meggar, or megohmmeter, typically uses a permanent magnet DC generator to produce the high voltage required for insulation resistance testing.

Question 13

In a meggar controlling torque is provided by
A)spring
B)gravity
C)coil
D)eddy current

Accepted Answer

The answer of In a meggar controlling torque is provided...

Question 14

The operating voltage of a meggar is about
A)6 v
B)12 v
C)40 v
D)100 v

Accepted Answer

The operating voltage of a megger, which is a type of insulation tester, is typically around 100 volts. This higher voltage is necessary to effectively test the insulation resistance of electrical wiring and equipment.

Question 15

Which of the following devices should be used for accurate measurement of low D.C. voltage ?
A)small range moving coil voltmeter
B)d.c. potentiometer
C)small range thermocouple voltmeter
D)none of the above

Accepted Answer

A d.c. potentiometer is specifically designed for the accurate measurement of low D.C. voltages. It measures voltage by comparing the unknown voltage with a known reference voltage, which allows for very precise measurements.

Question 16

It is required to measure the true open circuit e.m.f. of a battery. The best device is
A)d.c. voltmeter
B)ammeter and a known resistance
C)d.c. potentiometer
D)none of the above

Accepted Answer

A d.c. potentiometer is the most accurate device for measuring the true open circuit e.m.f. of a battery because it does not draw any current from the battery during the measurement, thus avoiding any voltage drop due to internal resistance, leading to a more accurate measurement of the battery's e.m.f.

Question 17

In an Anderson bridge, the unknown inductance is measured in terms of
A)known inductance and resistance
B)known capacitance and resistance
C)known resistance
D)known inductance

Accepted Answer

An Anderson bridge measures unknown inductance using a known capacitance and resistance, making it more precise for inductance measurement.

Question 18

If the current in a capacitor leads the voltage by 80°, the loss angle of the capacitor is
A)10°
B)80°
C)120°
D)170°

Accepted Answer

The loss angle of a capacitor is given by 90° minus the phase angle by which the current leads the voltage. Since the current leads the voltage by 80°, the loss angle is 90° - 80° = 10°.

Question 19

To avoid the effect of stray magnetic field in A.C. bridges we can use
A)magnetic screening
B)wagner earthing device
C)wave filters
D)any of the above

Accepted Answer

Magnetic screening is used to shield sensitive components from external magnetic fields, thus avoiding the effect of stray magnetic fields in A.C. bridges.

Question 20

Standard resistor is made from
A)platinum
B)maganin
C)silver
D)nichrome

Accepted Answer

Manganin is an alloy used for making standard resistors due to its low temperature coefficient of resistance and high stability.

Quiz 3: Electrical Measurement and Testing

Generally grounding is provided for:

Ground resistance should be designed such that:

The objective of earthing or grounding is:

The vale of resistance of an earthing electrode depends upon

A bridge circuit works at a frequency of 2KHz, the following can be used as detectors for detection of null conditions in the bridge:

Maxwell's inductance capacitance bridge is used for measurement of inductance of:

The wheatstone bridge cant be used for precision measurements because errors are introduce into on account of :

High resistances are provided with a guard terminal. This guard terminal is used to :

A potentiometer may be used for

--------- is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another,

For measuring a very high resistance we should use

The electrical power to a meggar is provided by

In a meggar controlling torque is provided by

The operating voltage of a meggar is about

Which of the following devices should be used for accurate measurement of low D.C. voltage ?

It is required to measure the true open circuit e.m.f. of a battery. The best device is

In an Anderson bridge, the unknown inductance is measured in terms of

If the current in a capacitor leads the voltage by 80°, the loss angle of the capacitor is

To avoid the effect of stray magnetic field in A.C. bridges we can use

Standard resistor is made from