31.What will happen if a voltmeter is connected like an ammeter in series of the load?
(a) The meter will burn out.
(b) The measurement will be too high.
(c) The same current will flow as would have been with an ammeter in circuit.
(d) There will be almost no current in the circuit
Ans: d
32. The pressure coil of a wattmeter consists of:
(a) More number of turns of fine wire
(b) Less number of turns of fine wire
(c) Less number of turns of thick wire
(d) More number of turns of thick wire
Ans: a
33. In a balanced 3-phases system, the current coil of a wattmeter is inserted in line 1 and the potential coil across 2 and 3. If the wattmeter reads 100 W, the reactive power drawn by the 3-phases load is
(a) 173.2 VAR
(b) 50 VAR
(c) 100 VAR
(d) 141.4 VAR
Ans: a
34.In an electrodynamometer type wattmeter:
(a) The current coil is made fixed
(b) The pressure coil is fixed
(c) Both the coil are fixed
(d) Both the coil are movable
Ans: a
35. In phantom loading arrangement, energy consumption in the calibration test of wattmeter is reduced because of
(a) The separate application of low voltage supply across the current coil
(b) No common point between the two coils
(c) The reduced loss in the current coil and pressure
(d) The absence of load in the test set
Ans: d
36. In a balanced 3-phases circuit, the line current is 12 A. When the power is measured by two wattmeter method, one meter reads 11 kW while the other reads zero. Power factor of the load is
(a) 0
(b) 0.5
(c) 0.866
(d) 1.0
Ans: b
37.A compensated wattmeter has its reading corrected for error due to
(a) Frequency
(b) Friction
(c) Power consumed in current coil
(d) Power consumed in pressure coil
Ans: d
38. One single phase wattmeter operating on 230 V and 5A for 4 hours makes 1940 revolutions. Meter constant in rev/kwh
(a) 422
(b) 450
(c) 415
(d) 400
Ans: a
39. For power measurement of three phase circuit by two wattmeter method, when the value of power factor is less than 0.5 lagging:
(a) One of the wattmeter will read zero.
(b) Both give the same readings
(c) One of the wattmeter connections will have to be reversed
(d) Pressure coil of the wattmeter will become ineffective
Ans: c
40.Single or one Wattmeter method can only be used for
(a) Balanced three-phase load
(b) Imbalanced two-phase load
(c) Balanced one-phase load
(d) Imbalanced one-phase load
Ans: a
41.The major cause for creeping in energy-meter is:
(a) Over compensation for friction
(b) Vibrations
(c) Stray magnetic fields
(d) Excessive voltage across the potential coil
Ans: a
42.The disc of domestic supply energy meter is made of which material?
(a) Zinc
(b) Copper
(c) Aluminum
(d) Silver
Ans: c
43.The pressure coil of an energy meter is……………..
(a) Purely resistive
(b) Purely inductive
(c) Highly resistive
(d) Highly inductive
Ans: d
44. If an induction type energy meter runs fast, it can be slowed down by:
(a) Lag adjustment
(b) Light load adjustment
(c) Adjusting the position of braking magnet and making it come closer to the centre of the disc
(d) Adjusting the position of braking magnet and making move away from the centre of the disc.
Ans: d
45. Two holes are drilled in the disc on a diameter of energy-meter to
(a) Increase ventilation
(b) Reduce the weight of disc
(c) Eliminate creeping on no-load
(d) Increase deflecting torque
Ans: c
46. Which instrument is used to measure the high resistance?
(a) Kelvin’s Double bridge
(b) Carey-Foster bridge
(c) Megger
(d) Wheat stone bridge
Ans: c
47. A megger is basically a/an
(a) Moving iron type instrument
(b) Moving coil type instrument
(c) Hot wire instrument
(d) Electrolytic instrument
Ans: b
48. Low resistance is measured by
(a) De sauty’s bridge
(b) Maxwell’s bridge
(c) Kelvin’s bridge
(d) Wien bridge
Ans: c
49. Schering bridge is used to measure
(a) Frequency
(b) Inductance
(c) Capacitance
(d) Mutual inductance
Ans: c
50. To measure the resistance of about 8 Ω which instrument should be used?
(a) Kelvin’s double bridge
(b) Wheatston’s bridge
(c) Meggar
(d) Wattmeter
Ans: b
51. In a 3 1⁄2 digit voltmeter, the largest number that can be read is:
(a) 1999
(b) 5999
(c) 9999
(d) 0999
Ans: a
52. A CRO can be used to measure-
(a) a.c. voltage
(b) d.c. voltage
(c) Frequency
(d) All of the above
Ans: d
53. In a CRO, a sinusoidal waveform of a certain frequency is displayed. The value of the quantity that can be made out by observation is
(a) RMS value of the sine wave
(b) Average value of the sine wave
(c) Form factor of the sine wave
(d) Peak-peak value of the sine wave
Ans: d
54. An inverse transducer converts
(a) Electrical energy to any other form of energy
(b) Electrical energy to light energy
(c) Mechanical displacement into electrical signal
(d) Electrical energy to mechanical form
Ans: a
55. Maxwell bridge is used to measure
(a) Inductance
(b) Capacitance
(c) Frequency
(d) None of the above
Ans: a
56. The dielectric loss of a capacitance can be measured by
(a) Hay bridge
(b) Maxwell bridge
(c) Anderson bridge
(d) Schering bridge
Ans: d
57. Which one of the following bridge is generally used for
measurement of frequency?
(a) Owen’s bridge
(b) Schering bridge
(c) Wien bridge
(d) Hay’s bridge
Ans: c
58. Hay bridge is suitable for measuring the following type of inductance
(a) having Q greater than 10
(b) having Q less than 10
(c) having any value of Q
(d) having a phase angle of reactance very large
Ans: a
59.The high torque to weight ratio in an analog indicating instrument indicates:
(a) High friction loss
(b) Low friction loss
(c) Not related to friction loss
(d) None of the above
Ans: b
60. What is the resolution of 4-digit digital instrument?
(a) 0.002%
(b) 0.005%
(c) 0.1%
(d) 0.01%
Ans: d
61. Lissajous pattern obtained on a CRO screen is a circle. Frequency of two
signals are
(a) Equal
(b) Unequal
(c) Zero
(d) Infinity
Ans: a
62. Modern electronic multimeters measure resistance by?
(a) Using an electronic bridge compensator for nulling
(b) Using a bridge circuit
(c) Using a electrical bridge circuit
(d) Forcing a constant current and measuring the voltage across the unknown resistance
Ans: d
63.In a Cathode Ray Tube, the focusing anode is located
(a) After accelerating anode
(b) Between pre-accelerating and accelerating anodes
(c) Before pre-accelerating anode
(d) Just after electron-gun
Ans: b
64.Megger is used for measure
(a) Very high resistance or insulation resistance
(b) Low resistance
(c) High resistance
(d) Very low resistance
Ans: a
65.In a meggar, the deflection of moving coil depends on-
(a) Applied voltage
(b) Inverse of applied voltage
(c) The ration of currents in the coil
(d) The product of currents in the coils
Ans: c
66. In which of the following transformers is the secondary
winding always kept closed
a) Current transformer
b) Potential transformer
c) Power transformer
d) Distribution transformer
Ans: a
67.Two holes are drilled in the disc on a diameter of energy-meter to
(a) Increase ventilation
(b) Reduce the weight of disc
(c) Eliminate creeping on no-load
(d) Increase deflecting torque
Ans: c
68. If an induction type energy meter runs fast, it can be slowed down by:
(a) Lag adjustment
(b) Light load adjustment
(c) Adjusting the position of braking magnet and making it come closer to the centre of the disc
(d) Adjusting the position of braking magnet and making move away from the centre of the disc
Ans: d
69.Following is not an advantage of a permanent magnet moving coil instrument
(a) It has a uniform scale
(b) It can be used without error for a long period of time
(c) It has good damping torque
(d) Its range can be easily extended
Ans: b
70.A Lissajous pattern on an oscilloscope has 5 horinzontal tangencies and 2 vertical tangencies. The frequency of horizontal input is 100 Hz. The frequency of the vertical will be
a)500 Hz
b)400Hz
c)250Hz
d)625Hz
Ans: c
71.For the measurement of low resistances, Kelvin’s double bridge has high accuracy because
a. It has two set of ratio arms which eliminates effect of resistance of connecting lead
b. It has a null indicating galvanometer
c. It has two null indicator
d. It has four sets of ratio arms which eliminates the effect of resistance
of connecting lead
Ans: a
72. In AC bridges, the Wagner earth devices are used to
a. Remove all the earth capacitances from the bridge circuit
b. Remove harmonics
c. Reduce error caused by stray electric field
d. All of these
Ans: a
73.Thermistor is a transducer. Its temperature coefficient is
a. Negative
b. Positive
c. Zero
d. None of these
Ans: a
74. In a measuring instrument, dead space is defined as the
a. Range of different input values over which there is no change in output values
b. Range of different output values for the same input values
c. Either (a) or (b)
d. None of these
Ans: a
75. In the absence of the restoring torque, the pointer
a. Will not deflect from its initial position
b. Will deflect but would not return to its zero position on removing current
c. Will deflect and return to its zero position on removing current
d. Will swing from minimum to maximum position
Ans: b
“TO SUCCESS IN YOUR MISSION YOU MUST HAVE SINGLE MINDED DEVOTION TO YOUR GOAL”
By- Dr. Kalam
For a detail explanation of each question, you can watch this video..