Multiple Choice Questions Topic Outline
- MCQs in Cells and Batteries
- MCQs in Electric Generator
- MCQs in Electronic Power Supply
- MCQs in Voltage Regulation
- MCQs in Photovoltaic/Thermoelectric Generator
- MCQs in Distribution Transformer
- MCQs in Uninterrupted Power Supply (UPS)
- MCQs in Float-Battery System
- MCQs in Converters
- MCQs in Inverters
The Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part 2 of the Series
51. The voltage of the bus bar to which several alternators are paralleled may be raised by simultaneously ______ of all alternators
- A. increasing field excitation
- B. decreasing field excitation
- C. increasing input to prime movers
- D. decreasing input to prime movers
52. The rating of an alternator is expressed in
- A. kW
- B. kVA
- C. HP
- D. KVAR
53. Cumulatively compounded motors are used in applications where ______ is required
- A. variable speed
- B. poor speed regulation
- C. sudden heavy loads for a short duration
- D. constant speed
54. Which motor never use belt connected loads?
- A. Series
- B. Commulatively compounded
- C. Shunt
- D. Differentially compounded
55. A standalone solar power system
- A. relies on the electric utility at night
- B. uses solar panels and batteries
- C. requires the use of dry cells
- D. need a full wave rectifier
56. A transformer will have zero efficiency at
- A. full load
- B. half full load
- C. no load
- D. twice the load
57. The efficiency of a transformer will be at maximum when
- A. leakage reactance of the two windings are equal
- B. resistance of the two windings are equal
- C. copper loss is equal to constant loss
- D. copper loss is zero
58. The armature winding of a dc Machine is ______ winding
- A. an open circuit
- B. a closed circuit
- C. partly open circuit and partly closed circuit
- D. lap
59. The speed at which a 6 pole alternator should be drive to generate 50 cycles per second is
- A. 1500 rpm
- B. 500 rpm
- C. 1000 rpm
- D. 1200 rpm
60. A 12v battery is rated at 48 ah. If it must deliver an average of 2.0a, how long will the battery last before it needs recharging
- A. 48 hrs
- B. 4 hrs
- C. 96 hrs
- D. 24 hrs
61. Connecting batteries of equal voltage in parallel
- A. multiplies the voltage available
- B. increases the internal resistance
- C. reduces the power available
- D. multiplies the current available
62. A storage battery in which the electrodes are grids of lead containing lead oxides that changes in composition during charging and discharging and the electrolyte is dilute sulfuric acid
- A. Leclanche battery
- B. Nickel cadmium battery
- C. Lead acid battery
- D. Faure storage battery
63. The common dry cell, which is a primary cell having a carbon positive electrode and a zinc negative electrode in an electrolyte of sal ammoniac and a depolarizer
- A. Leclanche cell
- B. Faure storage cell
- C. Lead acid cell
- D. Lithium cell
64. The maximum flux produced in the core of a transformer is
- A. directly proportional to supply frequency
- B. inversely proportional to supply frequency
- C. inversely proportional to primary voltage
- D. inversely proportional to secondary voltage
65. A transformer is so designed that primary and secondary windings have
- A. loose magnetic coupling
- B. tight magnetic coupling
- C. critical magnetic coupling
- D. good electric coupling
66. Four carbon zinc cell in series will provide about
- A. 2Vdc
- B. 6Vdc
- C. 9Vdc
- D. 8Vdc
67. What refers to a method in which the charger and the battery are always connected to each other for supplying current to the load
- A. Continuous charging
- B. Float charging
- C. Infinite charging
- D. On line charging
68. A series motor designed to operate on dc or ac
- A. Shunt motor
- B. Series motor
- C. Universal motor
- D. Compound motor
69. Combination of ac motor, dc generator, and exciter to provide adjustable voltage dc power to a dc motor.
- A. Ward-Leonard system
- B. Half wave SCR adjustable voltage supply
- C. Compound motor
- D. Universal motor
70. A motor takes a large current at starting because
- A. the armature resistance is high
- B. back emf is low
- C. back emf is high
- D. shunt field is producing weak field
71. A series motor will over speed when
- A. the load is increased
- B. the armature circuit is open
- C. the field id opened
- D. load is removed
72. When the load on an alternator is increased, the terminal voltage increases if the load power factor is
- A. unity
- B. leading
- C. lagging
- D. zero
73. The efficiency of the turbo-alternator ______ with increase in speed
- A. decreases
- B. remains the same
- C. increases
- D. becomes 100%
74. What is the output of a lead acid cell?
- A. 2.1V
- B. 1.5V
- C. 1.35V
- D. 1.25V
75. One of the following is a false statement
- A. storage cell has a reversible chemical reaction
- B. carbon zinc cell has unlimited shelf life
- C. lead acid cell is rechargeable
- D. primary cell is not rechargeable
76. In an alternator, the effect of armature reaction is minimum at power factor of
- A. 0.866 lagging
- B. 0.5 lagging
- C. 0.866 leading
- D. Unity
77. For given number of poles (2) and armature conductors, a lap winding will carry _____ a wave winding
- A. more current than
- B. same current as
- C. less current than
- D. half the current than
78. An 8 pole duplex lap winding will have ______ parallel paths
- A. 8
- B. 32
- C. 4
- D. 16
79. To increase the voltage output, cells are connected in
- A. parallel
- B. series-parallel
- C. parallel-series
- D. series
80. To increase current capacity, cells are connected in
- A. parallel
- B. series
- C. series- parallel
- D. parallel- series
81. Two things which are same for primary and secondary of transformer are
- A. ampere turns and voltage per turn
- B. resistance and leakage reactance
- C. current and inducted voltage
- D. number of turns and power
82. A transformer operates poorly at very low frequencies because
- A. permeability of core is increased
- B. magnetizing current is abnormally high
- C. primary reactance is too much
- D. permeability core is reduced
83. In an auto transformer, the primary and secondary are ______ coupled
- A. only magnetically
- B. magnetically as well as electrically
- C. only electrically
- D. directly
84. A storage battery in which the plates consist if lead antimony supporting grids covered with a lead oxide paste immersed in weak sulfuric acid
- A. Leclanche cell
- B. primary battery
- C. secondary battery
- D. Faure storage battery
85. Which of the following is a dry storage cell?
- A. Leclanche cell
- B. Edison cell
- C. Mercury cell
- D. Nickel cadmium cell
86. The field structure of a dc machine uses
- A. Salient pole arrangement
- B. Non salient pole arrangement
- C. Silicon steel
- D. Cast steel
87. Small Dc machines generally have _____ poles
- A. 4
- B. 2
- C. 6
- D. 8
88. The armature of a dc machine is laminated in order to reduce
- A. Eddy current loss
- B. Copper loss
- C. Hysteresis loss
- D. Frictional loss
89. To produce an output of 7.5v, how many carbon zinc cells are connected in series?
- A. 4
- B. 5
- C. 6
- D. 3
90. The demand for a large increase in torque of a dc series motor is met by a
- A. large decrease in current
- B. large increase in speed
- C. large decrease in speed
- D. small decrease in speed
91. As the load increases a, ______ motor will speed up
- A. series
- B. commutatively compounded
- C. shunt
- D. differentially compounded
92. The flux in the core of a single phase transformer is
- A. purely alternating one
- B. purely rotating one
- C. partly alternating and partly rotating
- D. constant
93. When the primary of a transformer is connected to a dc supply
- A. a primary draw small current
- B. primary leakage reactance is increased
- C. core losses are increased
- D. primary may burned out
94. a constant voltage source has
- A. High internal resistance
- B. minimum efficiency
- C. minimum current capacity
- D. low internal resistance
95. If the excitation of an alternator operating in parallel with other alternators is increased above the normal value excitation of excitation its
- A. power factor becomes more lagging
- B. output current decreases
- C. power factor becomes more leading
- D. output kw decreases
96. This synchronous reactance of an alternator is generally ______ armature resistance
- A. 5 times smaller than
- B. 10 – 100 times greater than
- C. 5 times greater than
- D. 10 times smaller than
97. DC series motors are used in those applications where _____ required
- A. high starting torque
- B. low no load speed
- C. constant speed
- D. variable speed
98. A dc motor is still used in industrial applications because it
- A. is cheap
- B. provides fine speed control
- C. is simple in construction
- D. has no replacement
99. The stator of n alternator is wound for ______ on the rotor
- A. a more number of poles than
- B. the same number of poles as
- C. less number of poles than
- D. twice the number of poles
100. Why are carbon brushes preferable compared to copper brushes?
- A. they have longer life
- B. they have lower resistance
- C. they are cheaper
- D. they reduce sparking
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