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All questions of Measurement and Measuring Instruments for Electrical Engineering (EE) Exam
Capacitive transducers are normally used for:- a)Static measurements
- b)Dynamic measurements
- c)Both static and dynamic measurements
- d)Transient measurements
Correct answer is option 'B'. Can you explain this answer?
Capacitive transducers are normally used for:
a)
Static measurements
b)
Dynamic measurements
c)
Both static and dynamic measurements
d)
Transient measurements
|
EduRev GATE answered |
Static measurement is the measurement of quantities which are slowly varying with time or mostly constant.
Dynamic measurement is the measurement of quantities which changes rapidly with time.
Capacitive transducers are used for dynamic measurements, used for measuring the displacement, pressure and other physical quantities.
An instrument transformer is used to extend the range of-- a)Induction instrument
- b)Electrostatic instrument
- c)Moving coil instrument
- d)PMMC instrument/PMMC
Correct answer is option 'A'. Can you explain this answer?
An instrument transformer is used to extend the range of-
a)
Induction instrument
b)
Electrostatic instrument
c)
Moving coil instrument
d)
PMMC instrument/PMMC
|
Rounak Banerjee answered |
Instrument transformers are of two types.
1. Potential transformer
2. Current transformer
These are used to extend the range of induction type of instruments.
Two 100 V full scale PMMC type DC voltmeters having figure of Merits (FOM) of 10 kΩ/V ad 20 kΩ/V are connected in series. The series combination can be sued to measure a maximum DC voltage of:
- a)200 V
- b)100 V
- c)300 V
- d)150 V
Correct answer is option 'D'. Can you explain this answer?
Two 100 V full scale PMMC type DC voltmeters having figure of Merits (FOM) of 10 kΩ/V ad 20 kΩ/V are connected in series. The series combination can be sued to measure a maximum DC voltage of:
a)
200 V
b)
100 V
c)
300 V
d)
150 V
|
Swara Dasgupta answered |
Solution:
Now IFSD 1=0.1mA ,IFSD2=0.05mA
So,voltmeter 2 reads the full scales current allowed is 0.05mA and and voltmeter one reads half of its full scale value so the total reading is 150V.
For accuracy of the instrument which is necessary- a)Conformity
- b)Precision
- c)Both
- d)None of the above
Correct answer is option 'C'. Can you explain this answer?
For accuracy of the instrument which is necessary
a)
Conformity
b)
Precision
c)
Both
d)
None of the above
|
Bijoy Kapoor answered |
In industrial instrumentation, accuracy is the measurement tolerance, or transmission of the instrument and defines the limits of the errors made when the instrument is used in normal operating conditions.
A wattmeter reads 25.34 W. The absolute error in measurement is -0.11 W. What is the true value of power:- a)25.23 W
- b)25.45 W
- c)-25.23 W
- d)-25.45 W
Correct answer is option 'B'. Can you explain this answer?
A wattmeter reads 25.34 W. The absolute error in measurement is -0.11 W. What is the true value of power:
a)
25.23 W
b)
25.45 W
c)
-25.23 W
d)
-25.45 W
|
Zoya Sharma answered |
Given that,
Measured value = 25.34 W
Absolute error = -0.11 W
Absolute error = Measured value – true value
⇒ -0.11 = 25.34 – true value
⇒ 25.34 + 0.11 = 25.45 W
A standard cell of 1.0185 V is used with a slide wire potentiometer. The balance was obtained at 60 cm. When an unknown emf was connected, the balance was obtained at 82 cm. What is the magnitude of unknownemf?- a)1.39 V
- b)0.75 V
- c)13.9 V
- d)7.45 V
Correct answer is option 'A'. Can you explain this answer?
A standard cell of 1.0185 V is used with a slide wire potentiometer. The balance was obtained at 60 cm. When an unknown emf was connected, the balance was obtained at 82 cm. What is the magnitude of unknownemf?
a)
1.39 V
b)
0.75 V
c)
13.9 V
d)
7.45 V
|
|
Zoya Sharma answered |
Given that,
Standard voltage Es = 1.0185V
The balance obtained at 60 cm.
Resistance Rs = 60Ω
Working current 
Voltage corresponding to 82 cm,
V = 0.0169 × 82 = 1.39V =
A single phase energy meter has a constant of 1200 revolution/kWh. When a load of 200 W is connected, the disc rotates at 4.2 revolutions per min. If the load is on for 10 hours, the meter records an excess of- a)0.1 kWh
- b)0.2 kWh
- c)1.0 kWh
- d)2.0 kWh
Correct answer is option 'A'. Can you explain this answer?
A single phase energy meter has a constant of 1200 revolution/kWh. When a load of 200 W is connected, the disc rotates at 4.2 revolutions per min. If the load is on for 10 hours, the meter records an excess of
a)
0.1 kWh
b)
0.2 kWh
c)
1.0 kWh
d)
2.0 kWh
|
Yash Patel answered |
True Kwh = 200 × 10 = 2 kWh
Given that, disc rotates at 4.2 revolutions per minute.
Recorded revolutions = 4.2 × 60 × 10 = 2520
Meter constant = 1200 revolution/kWh
Measured value of kWh = 2520/1200 = 2.1 kW
Excess value of record = measured value – true value = 2.1 – 2 = 0.1 kW
The power of 6-phase circuit can be measured with a minimum of:- a)1 wattmeter
- b)5 wattmeter
- c)3 wattmeter
- d)6 wattmeter
Correct answer is option 'B'. Can you explain this answer?
The power of 6-phase circuit can be measured with a minimum of:
a)
1 wattmeter
b)
5 wattmeter
c)
3 wattmeter
d)
6 wattmeter
|
Sharmila Kulkarni answered |
According to Blondel’s theorem the no. of watt-meters to be required to measure the total power in n-phase system is either N (or) (N – 1). When separate neutral wire is available in the system the no. of watt-meters to be required is N. When the neutral wire is not available in the system, then the no. of watt-meters to be required is (N – 1). One line is acts as a common line for return path.
Hence minimum number of watt-meters required = 5
For wire wound strain gauges, the gauge factor is defined as-- a)1 + v
- b)
- c)1 + 2v
- d)1 - v
Correct answer is option 'C'. Can you explain this answer?
For wire wound strain gauges, the gauge factor is defined as-
a)
1 + v
b)
c)
1 + 2v
d)
1 - v
|
Rhea Reddy answered |
The gauge factor is defined as the ratio of per unit change in resistance to per unit change in length.
Gauge factor, 
Where ε = strain = ΔL/L
The gauge factor can be written as
= Resistance change due to change of length + Resistance change due to change in area + Resistance change due to piezo resistive effect
If the change in the value of resistivity of a material when strained is neglected, the gauge factor is:
The above equation is valid only when Piezo resistive effect that is change in resistivity due to strain is almost neglected.
For wire wound strain gauges, Piezo resistive effect is almost negligible.
Which one of the following is a passive transducer?a)Piezoelectricb)Thermocouplec)Tachogeneratord)LVDTCorrect answer is option 'D'. Can you explain this answer?
b)Thermocouple
c)Tachogenerator
d)LVDT
Correct answer is option 'D'. Can you explain this answer?
|
Athira Pillai answered |
Transducers which require an external power source for their operation is called as a passive transducer. They produce an output signal in the form of some variation in resistance, capacitance or any other electrical parameter, which then has to be converted to an equivalent current or voltage signal. LVDT is an example of passive transducer. LVDT is used as an inductive transducer that convert motion into the electrical signal.
In which of the following do the measurements find their application? i. Automatic control of processes &operationsii. Engineering experimental analysisiii. Monitoring of processes and operations- a)i only
- b)i and ii
- c)ii and iii
- d)i, ii and iii
Correct answer is option 'D'. Can you explain this answer?
In which of the following do the measurements find their application?
i. Automatic control of processes &operations
ii. Engineering experimental analysis
iii. Monitoring of processes and operations
a)
i only
b)
i and ii
c)
ii and iii
d)
i, ii and iii
|
Aarav Sharma answered |
In automatic control of processes and operations, measurement is required to control and provide the desired response
In engineering experimental analysis, measurement is required to find out the response of system to inputs
To monitor a system or process we need measurement
The purpose of SYNC control in a CRO is to:- a)Focus the spot on the screen
- b)Lock the display of signal
- c)Set the intensity of spot
- d)Adjust the amplitude of display
Correct answer is option 'B'. Can you explain this answer?
The purpose of SYNC control in a CRO is to:
a)
Focus the spot on the screen
b)
Lock the display of signal
c)
Set the intensity of spot
d)
Adjust the amplitude of display
|
|
Rajdeep Gupta answered |
There must be synchronization between the sweep and the signal being measured. Synchronization is done to produce stationary pattern.
SYNC control in a CRO is used to lock the display of signal.
The vertical gain control of CRO is set at a deflection factor of 5 V/cm. An unknown sinusoidal is applied to Y-input. A 20 cm long straight line trace is observed, what will the ac voltage be?- a)17.677 V
- b)35.35 V
- c)100 V
- d)70.71 V
Correct answer is option 'C'. Can you explain this answer?
The vertical gain control of CRO is set at a deflection factor of 5 V/cm. An unknown sinusoidal is applied to Y-input. A 20 cm long straight line trace is observed, what will the ac voltage be?
a)
17.677 V
b)
35.35 V
c)
100 V
d)
70.71 V
|
Poulomi Ahuja answered |
Deflection sensitivity is defined as,
Deflection factor is the reciprocal of deflection sensitivity.
The value of resistances in a potential divider arrangement to convert a basic d Arsonval meter movement with an internal resistance of 100 Ω and a full scale current of 1 mA to a multi range DC voltmeter with ranges 0-150 V and 0-300 V are:- a)149.5 KΩ, 155.5 KΩ
- b)144.9 KΩ, 140 KΩ
- c)135.5 KΩ, 134 KΩ
- d)149.9 KΩ, 150 KΩ
Correct answer is option 'D'. Can you explain this answer?
The value of resistances in a potential divider arrangement to convert a basic d Arsonval meter movement with an internal resistance of 100 Ω and a full scale current of 1 mA to a multi range DC voltmeter with ranges 0-150 V and 0-300 V are:
a)
149.5 KΩ, 155.5 KΩ
b)
144.9 KΩ, 140 KΩ
c)
135.5 KΩ, 134 KΩ
d)
149.9 KΩ, 150 KΩ
|
Jyoti Basak answered |
To convert a basic D'Arsonval meter movement with an internal resistance of 100 Ω into a potential divider arrangement, we need to determine the resistances required to achieve the desired voltage range.
The basic formula for a potential divider is:
Vout = Vin * (R2 / (R1 + R2))
Where Vout is the output voltage, Vin is the input voltage, R1 is the resistance connected to the input side, and R2 is the resistance connected to the output side.
In this case, we want to convert the meter movement into a potential divider arrangement, so we need to determine the resistances required to achieve the desired voltage range.
Let's say we want the output voltage range to be from 0V to 5V.
At 0V output, the voltage across the meter movement will be 0V. Therefore, the resistance connected to the input side (R1) should be 0 Ω.
At 5V output, the voltage across the meter movement will be 5V. Therefore, the resistance connected to the output side (R2) should be equal to the internal resistance of the meter movement, which is 100 Ω.
Using the formula mentioned earlier, we can calculate the values for R1 and R2:
0V = Vin * (0 / (0 + 100))
0V = 0V
5V = Vin * (100 / (0 + 100))
5V = Vin * (100 / 100)
5V = Vin
From the calculations, we can see that the output voltage will be equal to the input voltage, meaning there is no voltage division happening. This is because we have set R1 to 0 Ω, effectively bypassing it.
Therefore, to convert the basic D'Arsonval meter movement into a potential divider arrangement with a 0V to 5V output range, we need to connect a resistor with a value of 100 Ω in series with the meter movement.
The basic formula for a potential divider is:
Vout = Vin * (R2 / (R1 + R2))
Where Vout is the output voltage, Vin is the input voltage, R1 is the resistance connected to the input side, and R2 is the resistance connected to the output side.
In this case, we want to convert the meter movement into a potential divider arrangement, so we need to determine the resistances required to achieve the desired voltage range.
Let's say we want the output voltage range to be from 0V to 5V.
At 0V output, the voltage across the meter movement will be 0V. Therefore, the resistance connected to the input side (R1) should be 0 Ω.
At 5V output, the voltage across the meter movement will be 5V. Therefore, the resistance connected to the output side (R2) should be equal to the internal resistance of the meter movement, which is 100 Ω.
Using the formula mentioned earlier, we can calculate the values for R1 and R2:
0V = Vin * (0 / (0 + 100))
0V = 0V
5V = Vin * (100 / (0 + 100))
5V = Vin * (100 / 100)
5V = Vin
From the calculations, we can see that the output voltage will be equal to the input voltage, meaning there is no voltage division happening. This is because we have set R1 to 0 Ω, effectively bypassing it.
Therefore, to convert the basic D'Arsonval meter movement into a potential divider arrangement with a 0V to 5V output range, we need to connect a resistor with a value of 100 Ω in series with the meter movement.
Deflection produced in Moving iron instruments is:- a)Proportional to rms value of operating current
- b)Proportional to square of rms value of operating current
- c)Inversely proportional to rms value of operating current
- d)Inversely proportional to square to rms value of operating current
Correct answer is option 'B'. Can you explain this answer?
Deflection produced in Moving iron instruments is:
a)
Proportional to rms value of operating current
b)
Proportional to square of rms value of operating current
c)
Inversely proportional to rms value of operating current
d)
Inversely proportional to square to rms value of operating current
|
Ritika Mukherjee answered |
The deflection in Moving iron instrument is given by,
Deflection is directly proportional to square of rms value of operating current
Which of the following is not suitable for the measurement of low resistances?- a)Kelvin’s Double Bridge method
- b)Ammeter Voltmeter method
- c)Potentiometer method
- d)Wheatstone Bridge
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not suitable for the measurement of low resistances?
a)
Kelvin’s Double Bridge method
b)
Ammeter Voltmeter method
c)
Potentiometer method
d)
Wheatstone Bridge
|
Arpita Banerjee answered |
Kelvin’s double bridge is used for the measurement of very low resistances. Using potentiometer method and Ammeter Voltmeter method we can measure low resistance.
Wheatstone bridge is suitable for the measurement of medium resistance
A pointer of the instrument once deflected returns to zero position when the current is removed due to:- a)Action of gravity
- b)Mass of the pointer
- c)Controlling torque
- d)Damping torque
Correct answer is option 'C'. Can you explain this answer?
A pointer of the instrument once deflected returns to zero position when the current is removed due to:
a)
Action of gravity
b)
Mass of the pointer
c)
Controlling torque
d)
Damping torque
|
|
Srestha Khanna answered |
The controlling torque is to control the pointer to a definite value which is proportional to quantity being measured. In absence of controlling torque, the pointer will swing beyond its final steady state position and the deflection will be indefinite. After removal of moving mechanism the pointer has to come back to its initial position, but in absence of controlling torque the pointer won’t come back to its initial position. The following mechanism can be used for producing controlling torque.
The deflecting torque is used for deflection, the controlling torque acts opposite to the deflecting torque. So before coming to rest the pointer always oscillates due to inertia, so to bring the pointer rest within a short time we will use damping torque without effecting controlling torque (or) inertia.
Which one of the following types of instruments does suffer from error due to magnetic hysteresis?- a)Induction type
- b)Electrodynamic
- c)Moving Iron
- d)PMMC
Correct answer is option 'C'. Can you explain this answer?
Which one of the following types of instruments does suffer from error due to magnetic hysteresis?
a)
Induction type
b)
Electrodynamic
c)
Moving Iron
d)
PMMC
|
|
Divya Kulkarni answered |
Hysteresis error in PMMC Instrument: It can be reduced by providing Al frame in the moving system since AL is having a thin hysteresis loop. So that the difference between magnetic fields is less. We can’t eliminate hysteresis error but we can reduce.
Hysteresis error in MI Instrument: Hysteresis error is more in MI instruments. Due to hysteresis effect, the value flux density for the same current, while ascending and descending are different. While descending, the flux density is high and while ascending it is lesser. So we can reduce this error by using small iron parts which can demagnetize quickly.
Hysteresis error in EMMC Instrument: Hysteresis error is absent in EMMC instruments, since there is no iron related material in the moving system.
Order of Hysteresis error in descending order
MI > PMMC > EMMC
Induction Type Instruments can be employed for ________.- a)Alternating Currents only
- b)Direct Current only
- c)AC and DC both
- d)Usually DC for heavy currents
Correct answer is option 'A'. Can you explain this answer?
Induction Type Instruments can be employed for ________.
a)
Alternating Currents only
b)
Direct Current only
c)
AC and DC both
d)
Usually DC for heavy currents
|
Gargi Mishra answered |
Induction type of instruments ae used to measure AC quantities only. We can use these instruments as an ammeter, voltmeter, wattmeter and an energy meter.
Perfect reproducibility means the instrument has- a)High accuracy
- b)Maximum drift
- c)Minimum accuracy
- d)No drift
Correct answer is option 'D'. Can you explain this answer?
Perfect reproducibility means the instrument has
a)
High accuracy
b)
Maximum drift
c)
Minimum accuracy
d)
No drift
|
|
Prashanth Mehra answered |
Reproducibility: It is the degree of closeness with which given value may be repeatedly measured. It may be specified in terms of units for a given period of time.
Perfect reproducibility means that the instrument has no drift.
No drift means that with a given input the measured values do not vary with time.
In a single phase induction type energy meter, the deflecting torque is________the true power in the circuit.- a)Proportional to
- b)Equal to
- c)Greater than
- d)Less than
Correct answer is option 'A'. Can you explain this answer?
In a single phase induction type energy meter, the deflecting torque is________the true power in the circuit.
a)
Proportional to
b)
Equal to
c)
Greater than
d)
Less than
|
|
Lakshmi Desai answered |
In a single phase induction type energy meter, the deflecting torque is directly proportional to the true power in the circuit.
An electrodynamometer type of instruments finds its major use as- a)Standard instrument only
- b)Transfer instrument only
- c)Both standard and transfer instruments
- d)An indicator type of instrument
Correct answer is option 'C'. Can you explain this answer?
An electrodynamometer type of instruments finds its major use as
a)
Standard instrument only
b)
Transfer instrument only
c)
Both standard and transfer instruments
d)
An indicator type of instrument
|
|
Tanishq Menon answered |
Precision type electrodynamometer is used in standardization process of potentiometer.
It is a transfer instrument. A transfer instrument is one which is calibrated with a d.c. source and used without any modifications for a.c. measurements. It has same accuracy for both D.C. and A.C. measurements.
Hence an electrodynamometer type of instruments are used as both standard and transfer instruments.
The ratio of output change for a given measuring system is referred to as- a)Sensitivity
- b)Linearity
- c)Stability
- d)Fidelity
Correct answer is option 'A'. Can you explain this answer?
The ratio of output change for a given measuring system is referred to as
a)
Sensitivity
b)
Linearity
c)
Stability
d)
Fidelity
|
Raj Desai answered |
Sensitivity: It is the change in output to the unit change in input
Linearity:The property of an instrument, if output varies linearly according to input is known as linearity. It is the ability to produce the input characteristics symmetrically and linearly. The graphical relationship between input and output is a straight line. It is also a supporting characteristic of accuracy.
One single phase wattmeter operating on 230 V and 5 A for 5 hours makes 1940 revolutions. Meter constant in revolution is 400. The power factor of the load will be:- a)1
- b)0.8
- c)0.7
- d)0.6
Correct answer is option 'B'. Can you explain this answer?
One single phase wattmeter operating on 230 V and 5 A for 5 hours makes 1940 revolutions. Meter constant in revolution is 400. The power factor of the load will be:
a)
1
b)
0.8
c)
0.7
d)
0.6
|
|
Akanksha Tiwari answered |
Given that,
Voltage (V) = 230 V
Current (I) = 5 A
Time (t) = 5 hours
Number of revolutions = 1940
Meter constant = 400
A spring controlled moving iron voltmeter draws a current of 1 mA for full scale value of 100 V. If it draws a current of 0.5 mA, the meter reading is:- a)25 V
- b)50 V
- c)100 V
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
A spring controlled moving iron voltmeter draws a current of 1 mA for full scale value of 100 V. If it draws a current of 0.5 mA, the meter reading is:
a)
25 V
b)
50 V
c)
100 V
d)
None of these
|
|
Arpita Banerjee answered |
For moving iron voltmeter,
Deflection (θ) is directly proportional to square of the current
Given that,
The power in a 3 phase circuit is measured with the help of 2 watt meters. The reading of one of watt meters is positive and that of the others is negative. The magnitude of readings is different. It can be concluded that the power factor of the circuit is- a)Unity
- b)2 (lagging)
- c)0.5 (lagging)
- d)Less than 0.5 (lagging)
Correct answer is option 'D'. Can you explain this answer?
The power in a 3 phase circuit is measured with the help of 2 watt meters. The reading of one of watt meters is positive and that of the others is negative. The magnitude of readings is different. It can be concluded that the power factor of the circuit is
a)
Unity
b)
2 (lagging)
c)
0.5 (lagging)
d)
Less than 0.5 (lagging)
|
|
Jyoti Choudhury answered |
We know that, power factor is given by
Given that,
W1 = +ve value
W2 = -ve value
Here power factor angle varies from 60 degrees to 90 degrees.
Hence power factor varies from zero to 0.5 lagging
The dead time of an instrument refers to _____.- a)Large change of input quantity for which there is no output.
- b)The time encountered when the instrument has to wait for some reactions to take place.
- c)The time before the instrument begins to response after the quantity has altered.
- d)Retardation or delay in the response of an instrument to a change in the input signal.
Correct answer is option 'C'. Can you explain this answer?
The dead time of an instrument refers to _____.
a)
Large change of input quantity for which there is no output.
b)
The time encountered when the instrument has to wait for some reactions to take place.
c)
The time before the instrument begins to response after the quantity has altered.
d)
Retardation or delay in the response of an instrument to a change in the input signal.
|
|
Ameya Nambiar answered |
Dead Time: It is the time before the instrument begins to response after the quantity has altered
Dead Space (or) Dead Zone: In some instruments, for some range of input values, there is no change in output. This range of input is called dead space (or) dead zone.
Which of the following is not a type of wattmeter?- a)Moving coil permanent magnet
- b)Induction
- c)Dynamometer
- d)Electrostatic
Correct answer is option 'A'. Can you explain this answer?
Which of the following is not a type of wattmeter?
a)
Moving coil permanent magnet
b)
Induction
c)
Dynamometer
d)
Electrostatic
|
|
Rajdeep Gupta answered |
Moving coil permanent magnet instrument can be used as ammeter and voltmeter but not as wattmeter.
Electrodynamometer instrument has two fixed coils and one moving coil. For using this instrument as a wattmeter to measure the power, the fixed coils act as a current coil and must be connected in series with a load. The moving coil acts as a pressure coil and must be connected across the supply terminals.
Electrostatic watt-meters are used for measurement of small amount of power, practically when the voltage is high and power factor is low. This type of wattmeter is also used for measurement of dielectric loss of cables on alternating voltage and for calibration of watt-meters and energy meters.
A null type of instrument as compared to a deflecting type instrument has- a)Higher accuracy
- b)Lower sensitivity
- c)Faster response
- d)All of the above
Correct answer is option 'A'. Can you explain this answer?
A null type of instrument as compared to a deflecting type instrument has
a)
Higher accuracy
b)
Lower sensitivity
c)
Faster response
d)
All of the above
|
|
Baishali Chopra answered |
The accuracy of null type instruments is higher than that of deflection type. This is because the opposing effect is calibrated with the help of standards which have high degree of accuracy. Accuracy of deflection type instruments is dependent upon their calibration which depends upon the instrument constants which are normally not known to a high degree of accuracy.
In the null type of instruments, the measured quantity is balanced out. This means the detector has to cover a small range around the balance (null) point and therefore can be made highly sensitive. Also the detector need not be calibrated since it has only to detect the presence and direction of unbalance and not the magnitude of unbalance. A deflection type of instrument must be larger in size, more rugged, and thus less sensitive if it is to measure large magnitude of unknown quantity.
Deflection type of instruments have faster response than null type instruments.
The disc of domestic supply energy meter is made of which material?- a)Zinc
- b)Copper
- c)Aluminium
- d)Silver
Correct answer is option 'C'. Can you explain this answer?
The disc of domestic supply energy meter is made of which material?
a)
Zinc
b)
Copper
c)
Aluminium
d)
Silver
|
|
Srestha Gupta answered |
The disc of domestic supply energy meter is made of aluminium.
Energy meter consists of rotating aluminium disc mounted on a spindle between two electro magnets.
The type of wattmeter commonly used for measurement of power in AC circuits is:- a)Moving iron type
- b)Thermocouple type
- c)Rectifier type
- d)Dynamometer type
Correct answer is option 'D'. Can you explain this answer?
The type of wattmeter commonly used for measurement of power in AC circuits is:
a)
Moving iron type
b)
Thermocouple type
c)
Rectifier type
d)
Dynamometer type
|
|
Sakshi Roy answered |
Dynamometer type instrument as wattmeter is used for the measurement of power in AC circuits
Moving iron type, rectifier type and thermocouple type instruments are mostly used as ammeter or voltmeter
The potentiometer wires should have _______:- a)High specific resistance and high temperature coefficient
- b)High specific resistance and low temperature coefficient
- c)Low specific resistance and high temperature coefficient
- d)Low specific resistance and low temperature
Correct answer is option 'B'. Can you explain this answer?
The potentiometer wires should have _______:
a)
High specific resistance and high temperature coefficient
b)
High specific resistance and low temperature coefficient
c)
Low specific resistance and high temperature coefficient
d)
Low specific resistance and low temperature
|
|
Vaishnavi Nair answered |
The potentiometer wires should have high resistivity (specific resistance) and low temperature coefficient. The alloys constantan and manganin are traditionally used for this purpose.
The current and potential coils of a dynamometer type wattmeter were accidentally interchanged while connecting. After energizing the circuit, it was observed that the wattmeter did not show the reading, this could be due to:- a)Damage to potential coils
- b)Damage to current coil
- c)Damage to both current coil and pressure
- d)Loose contacts
Correct answer is option 'B'. Can you explain this answer?
The current and potential coils of a dynamometer type wattmeter were accidentally interchanged while connecting. After energizing the circuit, it was observed that the wattmeter did not show the reading, this could be due to:
a)
Damage to potential coils
b)
Damage to current coil
c)
Damage to both current coil and pressure
d)
Loose contacts
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Abhay Kapoor answered |
Electrodynamometer instrument has two fixed coils and one moving coil. For using this instrument as a wattmeter to measure the power, the fixed coils acts as a current coil and must be connected in series with a load. The moving coil acts as a pressure coil and must be connected across the supply terminals.
In the question given that, the current and potential coils of a dynamometer type wattmeter were accidentally interchanged while connecting. Hence total voltage applies across current coil which has very less resistance which leads to damage the current coil.
Match List-I (Transducer) with List-2 (Characteristics) and select the correct answer using codes given below the lists:
- a)P-3, Q-2, R-4, S-1
- b)P-4, Q-3, R-2, S-1
- c)P-2, Q-1, R-4, S-3
- d)P-1, Q-2, R-3, S-4
Correct answer is option 'B'. Can you explain this answer?
Match List-I (Transducer) with List-2 (Characteristics) and select the correct answer using codes given below the lists:
a)
P-3, Q-2, R-4, S-1
b)
P-4, Q-3, R-2, S-1
c)
P-2, Q-1, R-4, S-3
d)
P-1, Q-2, R-3, S-4
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Srishti Choudhary answered |
Thermocouple has constant temperature at one end.
With a negative temperature coefficient thermistor, when the temperature increases the resistance will decreases.
A strain gauge is a sensor whose resistance varies with applied force. It converts force, pressure, tension, weight, etc., into a change in electrical resistance which can then be measured.
Linear variable differential transformer is a common type of electromechanical transducer that can convert the rectilinear motion of an object to which it is coupled mechanically into a corresponding electrical signal.
That would be the sensitivity of an ammeter, which requires a change of 3A in its coil to produce a change in deflection of the pointer by 6 mm?- a)0.4 mm/A
- b)0.4 A/mm
- c)2 mm/A
- d)2 A/mm
Correct answer is option 'C'. Can you explain this answer?
That would be the sensitivity of an ammeter, which requires a change of 3A in its coil to produce a change in deflection of the pointer by 6 mm?
a)
0.4 mm/A
b)
0.4 A/mm
c)
2 mm/A
d)
2 A/mm
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Ashwin Mukherjee answered |
Sensitivity: It is the change in output to the unit change in input
Change in the output = 6 mm
Change in input = 3 A
Sensitivity (S) = 6/3 = 2 mm/A
Which one of the following force is not needed for the satisfactory operation of any indicating (or measuring) instrument?- a)Controlling force
- b)Damping force
- c)Deflecting force
- d)Gravitational force
Correct answer is option 'D'. Can you explain this answer?
Which one of the following force is not needed for the satisfactory operation of any indicating (or measuring) instrument?
a)
Controlling force
b)
Damping force
c)
Deflecting force
d)
Gravitational force
|
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Jaya Rane answered |
In measuring instruments, the effect of unknown quantity is converted into a mechanical force which is transmitted to the pointer, which indicates on a scale. This moving system has to satisfy following requirements.
(1) Mechanism for producing deflecting torque
(2) Mechanism for producing controlling torque
(3) Mechanism for producing damping torque
Hence gravitational force is not needed for the satisfactory operation of any indicated instrument.
According to Blondel’s theorem, if a network is supplied using ‘n’ conductor’s the total power is ________ of the reading of n wattmeter’s so arranged that a current coil of each wattmeter is in each line and the corresponding pressure coil is connected between that line and a common point- a)Sum
- b)Product
- c)Sum of products of two wattmeter’s reading taken together
- d)Difference
Correct answer is option 'A'. Can you explain this answer?
According to Blondel’s theorem, if a network is supplied using ‘n’ conductor’s the total power is ________ of the reading of n wattmeter’s so arranged that a current coil of each wattmeter is in each line and the corresponding pressure coil is connected between that line and a common point
a)
Sum
b)
Product
c)
Sum of products of two wattmeter’s reading taken together
d)
Difference
|
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Sanaya Basu answered |
According to Blondel’s theorem the number of wattmeters to be required to measure the total power in n-phase system is either N or(N-1).
When separate neutral wire is available in the system the no. of watt meters to be required is N.
When the neutral wire is not available in the system, then the no. of watt meters to be required is (N-1). One line is acts as a common line for return path.
The total power is the sum of the all wattmeter readings.
Which meter is suitable for the measurement of 10 mV at 50 MHz?- a)Moving iron voltmeter
- b)CRO
- c)Electrostatic voltmeter
- d)VTVM
Correct answer is option 'B'. Can you explain this answer?
Which meter is suitable for the measurement of 10 mV at 50 MHz?
a)
Moving iron voltmeter
b)
CRO
c)
Electrostatic voltmeter
d)
VTVM
|
|
Madhurima Das answered |
CRO is used to measure the quantities at higher frequencies. Hence CRO is suitable for the measurement of 10 mV at 50 MHz.
A piezometer is used to measure:- a)Strain in structure
- b)Very low pressure
- c)Very high pressure
- d)Leakage reactance
Correct answer is option 'B'. Can you explain this answer?
A piezometer is used to measure:
a)
Strain in structure
b)
Very low pressure
c)
Very high pressure
d)
Leakage reactance
|
|
Nishtha Chauhan answered |
A piezometer is a device used to measure liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity. It is used to measure very low pressures.
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RRB JE for Electrical Engineering
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