ELECTRICAL ENGINEERING- PAGE 8
ELECTRICAL ENGINEERING MCQs- PAGE 8
1. In a steam turbine cycle, the lowest pressure occurs in
(A) Boiler
(B) Condenser
(C) Super heater
(D) Turbine inlet
Ans: B
2. A network having more than one source of emf is known as
(A) Active network
(B) Passive network
(C) Linear network
(D) Non linear network
Ans: A
3. The Electrolyte used in a lead acid cell is
(A) Manganese dioxide
(B) Sulphuric acid and water
(C) Concentrated sulphuric acid
(D) Distilled water
Ans: B
4. At resonance condition the power factor of the circuit is
(A) Zero (B) Lagging
(C) Leading (D) Unity
Ans: D
5. Compensating winding is employed in an AC series motor in order to
(A) increase the total torque
(B) compensate for decrease in field flux
(C) reduce effects of armature reaction
(D) reduce the sparking at brushes
Ans: C
6· In a Synchronous motor damper winding is provided in order to
(A) Stabilise rotor rotation
(B) Suppress rotor oscillations
(C) Develop necessary starting torque
(D) Both (B) and (C)
Ans: D
7. The full load voltage regulation of an alternator is -2%. This indicates that the load power factor is
(A) unity
(B) lagging
(C) either unity or lagging
(D) leading
Ans: D
8. In medium transmission lines the shunt capacitance is taken into account in
(A) T-method
(B) π -method
(C) Steinmetz method
(D) All of the above
Ans: D
9. When the stator supply voltage frequency is f, then the frequency of the rotor current.
(A) f
(C) 2f
(B) 0
(D) sf
Ans: D
10. The power factor of an alternator is determined by its
(A) Speed (B) Prime mover
(C) Load (D) Excitation
Ans: C
11. The sodium vapour lamp is filled with ------ gas at a pressure of 10 mm of mercury.
(A) oxygen
(B) Neon
(C) nitrogen
(D) hydrogen
Ans: B
12. The effect of armature reaction under zero power factor lagging load condition
(A) Cross magnetising effect
(B) Magnetising effect
(C) Demagnetising effect
(D) Distortion
Ans: C
13. When a 400 Hz transformer is operated at 50 Hz, its kVA rating is
(A) unaffected
(B) increased 8 times
(C) increased 64 times
(D) reduced to 1/8
Ans: D
14. A Transformer works on the principle of
(A) Mutual induction
(B) Self induction
(C) Faradays law of electromagnetic induction
(D) Electromagnetic induction
Ans: A
15. Induction instruments have found widest applications as
(A) Watt hour meter
(B) Voltmeter
(C) Ammeter
(D) Frequency meter
Ans: A
16. The major cause for creeping is
(A) Lighting load
(B) Capacitive load
(C) Over compensation for friction
(D) Over load compensation
Ans: C
17. The power consumption of PMMC instrument is typically about
(A) 0.25W to 2W
(B) 25 Micro watt to 200 micro watt
(C) 2.5 milli watt to 20 milli watt
(D) 0.25 milli watt to 200 milliwatt
Ans: B
18. According to safety, the resistance of earthing electrode should be
(A) Low (B) Medium
(C) High (D) Does not affect
Ans: A
19. If the insulation between two conductors is faulty, a current flows between them. This is called as
(A) Open circuit fault
(B) Short circuit fault
(C) Ground fault
(D) Cable fault
Ans: B
20. Fluid friction damping can be used in
(A) Horizontally mounted instruments
(B) Vertically mounted instruments
(C) Both vertical and horizontal instruments
(D) Plane surface instruments
Ans: B
21. The advantage of Varley loop tests over Murray loop tests is
(A) they can be used for localizing of short circuit faults
(B) they can be used for localizing of earth fault
(C) the loop resistance can be experimentally determined
(D) their accuracy is higher
Ans: C
22. A moving coil instrument can be used as an ammeter by connecting a suitable resistance
(A) in series
(B) in parallel
(C) in series - parallel combination
(D) in series with another resistance
Ans: B
23. 1 unit is __________ (A) 500wh (B) 1000 wh
(C) 10,000wh (D) 1000 kwh
Ans: B
24. Type of instrument range can be extended by connecting a shunt across its terminals
(A) Moving Iron voltmeter
(B) Moving Iron ammeter
(C) Dynamometer type
(D) Energy meter
Ans: B
25. A DIAC is a-------switch.
(A) 2 terminal in directional switch
(B) 2 terminal bi-directional switch
(C) 3 terminal bi-directional switch
(D) 4 terminal bi-directional switch
Ans: B
26. The distance between two Consecutive Rivets is called
(A) Pitch
(B) Gauge line
(C) Gauge distance
(D) Back pitch
Ans: C
27. A tunnel diode
(A) has a small tunnel in its junction
(B) is a point contact diode
(C) is a gallium arsenid device
(d) is a highly doped P-N junction device
Ans: D
28. The voltage gain of a common collector configuration is
(A) above 150
(B) above 500
(C) zero
(D) less than 1
Ans: D
29. The arrow in the symbol of a transistor indicates the direction of
(A) Electron current in the emitter
(B) Electron current in the collector
(C) Hole current in the emitter
(D) Donor ion current
Ans: C
30. A JFET is a - -----controlled semiconductor device.
(A) Voltage (B) Current
(C) Power (D) None of the above
Ans: A
31. A TRIAC behaves like two
(A) Diodes in series
(B) Inverse parallel connected SCR with common gate.
(C) Four layer diodes in parallel
(D) Resistor and one diode
Ans: B
32. In thyristor, holding current is
(A) More than latching current
(B) Less than the latching current .
(C) Equal to latching current
(D) Equal to gate current
Ans: B
33. The varactor diode changes the capacitance value in terms of
(A) Micro farads (B) Pico farads
(C) Farads (D) Milli farads
Ans: B
34. The output voltage of IC 7905 is
(A) +5V (B) -5V
(C) -9V (D) +9V
Ans: B
35. A voltage regulator provides-----voltage.
(A) constant input
(B) constant output
(C) varying input
(D) varying output
Ans: B
36. The percentage voltage regulation of a ideal voltage regulator is
(A) Above 95%
(B) 100%
(C) 0%
(D) Negative
Ans: C
37. Which rectifier require four diodes?
(A) Half-wave voltage doubler
(B) Full-wave voltage doubler
(C) Full-wave bridge circuit
(D) Voltage tripler
Ans: C
38. Hartley oscillator use ------inductors in the tank circuit.
(A) 1
(B) 2
(C) 3
(D) 4
Ans: B
39. The rivets are generally made of
(A) Brass (B) Tin
(C) Steel (D) Copper
Ans: C
40. Full adder has ______ inputs.
(A) 1 (B) 2 (C) 3 (D) 0
Ans: C
41. Consider the following statements :
Assertion (A) : Data selection from one of many inputs is multiplexer and send to output
Reason (R) : In telephone transmission systems, one telephone line will be used for more than one input
(A) (A) is true but (R) is not true
(B) (A) is true, (R) is true
(C) (A) is not true but (R) is true
(D) (A) and (R) are true but (R) is not correct explanation of (A)
Ans: B
42. In a ripple counter clock pulses are applied to clock input of-----Flip Flop.
(A) 4 (B) 3
(C) 1 (D) 2
Ans: C
43. Consider the following statements :
Assertion (A) : Counter is used to count the number of clock cycles
Reason (R) : Clock pulses occur at known intervals counter measure time, period, frequency.
(A) (A) is true (R) is true
(B) (A) is true (R) is not true
(C) (A) is true (R) is not correct explanation to (A)
(D) (A) and (R) is true (R) is correct explanation to (A)
Ans: A
44. Capable of clearing high as well as low fault current, require no maintenance don't deteriorate with age, high speed of operation
(A) High-Rupturing Capacity (H.R.C) Fuse
(B) Semi-enclosed rewirable fuse
(C) Metal clad fuses
(D) Liquid type fuses
Ans: A
45. The value of fusing factor is preferably
(A) zero
(B) less than unity
(C) unity
(D) greater than unity
Ans: D
46. Super tension cables are
(A) from 33 kV to 66 kV
(B) from 22 kV to 33 kV
(C) upto 11 kV
(D) beyond 132 kV
Ans: B
47. In hydro power plants
(A) Initial cost is high and operating cost is low
(B) Initial cost as well as operating costs are high
(C) Initial cost is low and operating cost is high
(D) Initial cost as well as operating cost is low
Ans: A
48. The Booster is inserted in the circuit to
(A) Increase current
(B) Compensate for voltage drop
(C) Reduce voltage drop
(D) Reduce current
Ans: B
49. Which type of insulators are used on 132 kV transmission line?
(A) Pin type
(B) Disc type
(C) Shackle type
(D) Pin and shackle type
Ans: B
50. Which alternator will have more no. of poles?
(A) Coupled to hydraulic turbine
(B) Coupled to steam turbine
(C) Coupled to gas turbine
(D) All will have same no. of poles
Ans: A
51. HRC fuse is a
(A) Low voltage fuse (B) High voltage fuse
(C) I Metal clad fuse (D) Circuit breaker
Ans: A
(A) Boiler
(B) Condenser
(C) Super heater
(D) Turbine inlet
Ans: B
2. A network having more than one source of emf is known as
(A) Active network
(B) Passive network
(C) Linear network
(D) Non linear network
Ans: A
3. The Electrolyte used in a lead acid cell is
(A) Manganese dioxide
(B) Sulphuric acid and water
(C) Concentrated sulphuric acid
(D) Distilled water
Ans: B
4. At resonance condition the power factor of the circuit is
(A) Zero (B) Lagging
(C) Leading (D) Unity
Ans: D
5. Compensating winding is employed in an AC series motor in order to
(A) increase the total torque
(B) compensate for decrease in field flux
(C) reduce effects of armature reaction
(D) reduce the sparking at brushes
Ans: C
6· In a Synchronous motor damper winding is provided in order to
(A) Stabilise rotor rotation
(B) Suppress rotor oscillations
(C) Develop necessary starting torque
(D) Both (B) and (C)
Ans: D
7. The full load voltage regulation of an alternator is -2%. This indicates that the load power factor is
(A) unity
(B) lagging
(C) either unity or lagging
(D) leading
Ans: D
8. In medium transmission lines the shunt capacitance is taken into account in
(A) T-method
(B) π -method
(C) Steinmetz method
(D) All of the above
Ans: D
9. When the stator supply voltage frequency is f, then the frequency of the rotor current.
(A) f
(C) 2f
(B) 0
(D) sf
Ans: D
10. The power factor of an alternator is determined by its
(A) Speed (B) Prime mover
(C) Load (D) Excitation
Ans: C
11. The sodium vapour lamp is filled with ------ gas at a pressure of 10 mm of mercury.
(A) oxygen
(B) Neon
(C) nitrogen
(D) hydrogen
Ans: B
12. The effect of armature reaction under zero power factor lagging load condition
(A) Cross magnetising effect
(B) Magnetising effect
(C) Demagnetising effect
(D) Distortion
Ans: C
13. When a 400 Hz transformer is operated at 50 Hz, its kVA rating is
(A) unaffected
(B) increased 8 times
(C) increased 64 times
(D) reduced to 1/8
Ans: D
14. A Transformer works on the principle of
(A) Mutual induction
(B) Self induction
(C) Faradays law of electromagnetic induction
(D) Electromagnetic induction
Ans: A
15. Induction instruments have found widest applications as
(A) Watt hour meter
(B) Voltmeter
(C) Ammeter
(D) Frequency meter
Ans: A
16. The major cause for creeping is
(A) Lighting load
(B) Capacitive load
(C) Over compensation for friction
(D) Over load compensation
Ans: C
17. The power consumption of PMMC instrument is typically about
(A) 0.25W to 2W
(B) 25 Micro watt to 200 micro watt
(C) 2.5 milli watt to 20 milli watt
(D) 0.25 milli watt to 200 milliwatt
Ans: B
18. According to safety, the resistance of earthing electrode should be
(A) Low (B) Medium
(C) High (D) Does not affect
Ans: A
19. If the insulation between two conductors is faulty, a current flows between them. This is called as
(A) Open circuit fault
(B) Short circuit fault
(C) Ground fault
(D) Cable fault
Ans: B
20. Fluid friction damping can be used in
(A) Horizontally mounted instruments
(B) Vertically mounted instruments
(C) Both vertical and horizontal instruments
(D) Plane surface instruments
Ans: B
21. The advantage of Varley loop tests over Murray loop tests is
(A) they can be used for localizing of short circuit faults
(B) they can be used for localizing of earth fault
(C) the loop resistance can be experimentally determined
(D) their accuracy is higher
Ans: C
22. A moving coil instrument can be used as an ammeter by connecting a suitable resistance
(A) in series
(B) in parallel
(C) in series - parallel combination
(D) in series with another resistance
Ans: B
23. 1 unit is __________ (A) 500wh (B) 1000 wh
(C) 10,000wh (D) 1000 kwh
Ans: B
24. Type of instrument range can be extended by connecting a shunt across its terminals
(A) Moving Iron voltmeter
(B) Moving Iron ammeter
(C) Dynamometer type
(D) Energy meter
Ans: B
25. A DIAC is a-------switch.
(A) 2 terminal in directional switch
(B) 2 terminal bi-directional switch
(C) 3 terminal bi-directional switch
(D) 4 terminal bi-directional switch
Ans: B
26. The distance between two Consecutive Rivets is called
(A) Pitch
(B) Gauge line
(C) Gauge distance
(D) Back pitch
Ans: C
27. A tunnel diode
(A) has a small tunnel in its junction
(B) is a point contact diode
(C) is a gallium arsenid device
(d) is a highly doped P-N junction device
Ans: D
28. The voltage gain of a common collector configuration is
(A) above 150
(B) above 500
(C) zero
(D) less than 1
Ans: D
29. The arrow in the symbol of a transistor indicates the direction of
(A) Electron current in the emitter
(B) Electron current in the collector
(C) Hole current in the emitter
(D) Donor ion current
Ans: C
30. A JFET is a - -----controlled semiconductor device.
(A) Voltage (B) Current
(C) Power (D) None of the above
Ans: A
31. A TRIAC behaves like two
(A) Diodes in series
(B) Inverse parallel connected SCR with common gate.
(C) Four layer diodes in parallel
(D) Resistor and one diode
Ans: B
32. In thyristor, holding current is
(A) More than latching current
(B) Less than the latching current .
(C) Equal to latching current
(D) Equal to gate current
Ans: B
33. The varactor diode changes the capacitance value in terms of
(A) Micro farads (B) Pico farads
(C) Farads (D) Milli farads
Ans: B
34. The output voltage of IC 7905 is
(A) +5V (B) -5V
(C) -9V (D) +9V
Ans: B
35. A voltage regulator provides-----voltage.
(A) constant input
(B) constant output
(C) varying input
(D) varying output
Ans: B
36. The percentage voltage regulation of a ideal voltage regulator is
(A) Above 95%
(B) 100%
(C) 0%
(D) Negative
Ans: C
37. Which rectifier require four diodes?
(A) Half-wave voltage doubler
(B) Full-wave voltage doubler
(C) Full-wave bridge circuit
(D) Voltage tripler
Ans: C
38. Hartley oscillator use ------inductors in the tank circuit.
(A) 1
(B) 2
(C) 3
(D) 4
Ans: B
39. The rivets are generally made of
(A) Brass (B) Tin
(C) Steel (D) Copper
Ans: C
40. Full adder has ______ inputs.
(A) 1 (B) 2 (C) 3 (D) 0
Ans: C
41. Consider the following statements :
Assertion (A) : Data selection from one of many inputs is multiplexer and send to output
Reason (R) : In telephone transmission systems, one telephone line will be used for more than one input
(A) (A) is true but (R) is not true
(B) (A) is true, (R) is true
(C) (A) is not true but (R) is true
(D) (A) and (R) are true but (R) is not correct explanation of (A)
Ans: B
42. In a ripple counter clock pulses are applied to clock input of-----Flip Flop.
(A) 4 (B) 3
(C) 1 (D) 2
Ans: C
43. Consider the following statements :
Assertion (A) : Counter is used to count the number of clock cycles
Reason (R) : Clock pulses occur at known intervals counter measure time, period, frequency.
(A) (A) is true (R) is true
(B) (A) is true (R) is not true
(C) (A) is true (R) is not correct explanation to (A)
(D) (A) and (R) is true (R) is correct explanation to (A)
Ans: A
44. Capable of clearing high as well as low fault current, require no maintenance don't deteriorate with age, high speed of operation
(A) High-Rupturing Capacity (H.R.C) Fuse
(B) Semi-enclosed rewirable fuse
(C) Metal clad fuses
(D) Liquid type fuses
Ans: A
45. The value of fusing factor is preferably
(A) zero
(B) less than unity
(C) unity
(D) greater than unity
Ans: D
46. Super tension cables are
(A) from 33 kV to 66 kV
(B) from 22 kV to 33 kV
(C) upto 11 kV
(D) beyond 132 kV
Ans: B
47. In hydro power plants
(A) Initial cost is high and operating cost is low
(B) Initial cost as well as operating costs are high
(C) Initial cost is low and operating cost is high
(D) Initial cost as well as operating cost is low
Ans: A
48. The Booster is inserted in the circuit to
(A) Increase current
(B) Compensate for voltage drop
(C) Reduce voltage drop
(D) Reduce current
Ans: B
49. Which type of insulators are used on 132 kV transmission line?
(A) Pin type
(B) Disc type
(C) Shackle type
(D) Pin and shackle type
Ans: B
50. Which alternator will have more no. of poles?
(A) Coupled to hydraulic turbine
(B) Coupled to steam turbine
(C) Coupled to gas turbine
(D) All will have same no. of poles
Ans: A
51. HRC fuse is a
(A) Low voltage fuse (B) High voltage fuse
(C) I Metal clad fuse (D) Circuit breaker
Ans: A
52. The mechanical power developed in a d.c. motor is equal to
(a) power input – core losses (b) power input – mechanical losses
(c) Armature current × counter e.m.f. (d) Armature current × supply voltage
Ans: C
53. An electric train employing a d.c. series motor is running at a fixed speed. When a sudden drop in voltage of supply takes place, then this results in
(a) drop in speed and rise in current. (b) rise in speed and drop in current.
(c) rise in speed and rise in current. (d) drop in speed with current unaltered.
Ans: B
54. A 220 V dc shunt motor is running at 500 rpm when armature current is 50 A. The value of armature resistance is 0.2 ohm. The speed of motor at the double torque will be
(a) 250 rpm (b) 500 rpm (c) 1000 rpm (d) 476 rpm
Ans: D
55. A 10 kVA 220 V/220 V, 50 Hz transformer shows 340 W in short circuit test and 168 W in open circuit test. Its efficiency at full load and 0.8 power factor lagging is approximately
(a) 92% (b) 94% (c) 96% (d) 98%
Ans: B
56. If number of poles in lap wound d.c. generator are doubled, the generated e.m.f. will be
(a) increased by a factor of 2 (b) decreased by a factor of 2 (c) increased by a factor of 4 (d) unchanged
Ans: D
57. The material of hair spring used in measuring instruments is made of which of material of the following :
(a) Copper (b) Bronze (c) Alnico (d) None of theseAns: B
58. The most common type of prime mover used for low speed alternators is
(a) Steam turbine (b) Petrol engine (c) Hydraulic turbine (d) Diesel engine
Ans: C
59. When speed of an alternator is changed from 3600 rpm to 1800 rpm, the generated emf will be
(a) one-half (b) twice (c) one-fourth (d) four times
Ans: A
60. The power factor of an alternator is determined by its
(a) prime mover (b) speed (c) excitation (d) load
Ans: D
61. The efficiency of an ordinary transformer is maximum when
(a) it runs at half of full speed (b) it runs at full load (c) copper losses are equal to iron losses (d) it runs at slightly overload
Ans: C
62. At light load, efficiency of a transformer is low. It is because
(a) copper loss is small. (b) copper loss is high. (c) secondary output is low. (d) fixed loss is high with respect to output.
Ans: D
63. The essential condition for parallel operation of two single phase transformers is that they should have the same
(a) Polarity (b) kVA rating (c) Voltage ratio (d) Percentage impedance
Ans: A
64. A transformer transforms
(a) frequency only (b) voltage only (c) current only (d) voltage and current
Ans: D
65. Which of the following connections of a three phase transformer are best suited for 3-phase, 4-wire service ?
(a) ∆ – ∆ (b) ϒ – ϒ (c) ∆ – ϒ (d) ϒ – ∆
Ans: C
66. Transformers are rated in kVA instead of kW, because
(a) load power factor is often not known. (b) total transformer loss depends on volt-ampere.
(c) kVA is fixed where as kW depends on load power factor. (d) None of the above
Ans: B
67. A transformer has negative voltage regulation when its load power factor is
(a) Zero (b) Leading (c) Unity (d) Lagging
Ans: B
68. A 4-pole dc generator runs at 1500 rpm. The frequency of current in armature winding is
(a) zero (b) 25 Hz (c) 50 Hz (d) 100 Hz
Ans: C
69. The no load current in a transformer lags the supply voltage by
(a) 0° (b) 90° (c) 110° (d) about 75°
Ans: D
70. Two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively. The highest speed of alternators is
(a) 600 rpm (b) 500 rpm (c) 3000 rpm (d) 3600 rpm
Ans: A
71. The heat run test of a transformer without its loading is performed by means of
(a) Short circuit test (b) Open circuit test (c) Half time short circuit test and half time open circuit test (d) Sumpner’s test
Ans: D
73. A d.c. series motor should never be started at
(a) normal load condition. (b) full load condition. (c) no load condition. (d) slightly overload condition.
Ans: C
74. In a d.c. generator, 8 parallel paths and 16 brushes for collection of current are used. If voltage drop per brush is 1 V, then reduction in the induced e.m.f. will be
(a) 2 V (b) 4 V (c) 8 V (d) 16 V
Ans: A
75. The input impedance of a common base transistor is
(a) Medium (b) Low (c) High (d) Infinity
Ans: B
76. Transistor can be operated in
(a) active region only (b) cut-off region only (c) saturation region only (d) All of the above
Ans: D
78. For any inverting amplifier, the input capacitance due to Miller effect
(a) increases (b) decreases (c) remains constant (d) None of these
Ans: A
79. In an amplifier, if voltage shunt negative feedback is employed, then
(a) the bandwidth decreases (b) the output resistance decreases (c) the input resistance decreases (d) the gain increases
Ans: B
80. Feedback in an amplifier is used to
(a) control output (b) increase gain (c) decrease input resistance (d) stabilize gain
Ans: A
81. In which material, valence electrons are tightly bounded to their parent atoms ?
(a) Conductor (b) Semiconductor (c) Insulator (d) Magnetic Ans: C
82. The disc of domestic supply energy meter is made of which material ?
(a) Zinc (b) Copper (c) Aluminium (d) Silver Ans: C
83. When used as a voltage regulator, a zener diode is normally
(a) forward biased (b) reversed biased (c) not biased (d) None of the above
Ans: B
84. Ferrites are types of
(a) magnetic material (b) conducting material (c) semiconducting material (d) insulating material Ans: A
85. In a single stage amplifier D.C and A.C load lines
(a) are always parallel (b) are perpendicular to each other
(c) cross each other at Q-point (d) are inclined but do not cross each other
Ans: C
86. Super conducting materials can be used for
(a) ore refining. (b) magnetic levitation in high speed trains. (c) medical resonance imaging. (d) All of the above Ans: D
87. Improper biasing of a transistor circuit leads to
(a) excessive heat production in collector.(b) faulty location of load line. (c) heavy loading of emitter. (d) distortion in output signal.
Ans: D
88. When a P-N junction is reverse biased
(a) it offers high resistance (b) its depletion layer becomes narrow (c) its barrier potential decreases (d) it breaks down
Ans: A
89. The current gain of a common emitter transistor is 50. The change in emitter current for a corresponding change of 5 mA in base current will be
(a) 50 mA (b) 55 mA (c) 250 mA (d) 255 mA
Ans: D
90. If the maximum current of a half-wave rectified wave is 10 A, its r.m.s value is given by
(a) 3.10 A (b) 5.0 A (c) 6.37 A (d) 7.07 A
Ans: B
91. A common emitter amplifier is characterized by
(a) low voltage gain (b) very high output impedance (c) moderate power gain (d) signal phase reversal
Ans: D
92. The maximum rectification efficiency of a half-wave rectifier is
(a) 40.6% (b) 81.2% (c) 88.0% (d) 100%
Ans: A
93. The ripple factor of a power supply is a measure of
(a) its filter efficiency (b) its voltage regulation (c) its purity of output (d) diode rating
Ans: C
94. The power dissipation in a transistor is the product of
(a) Emitter current and emitter to base voltage. (b) Collector current and collector to base voltage.
(c) Emitter current and collector to emitter voltage. (d) None of the above
Ans: B
95. Consider the following circuit configurations : 1. Common emitter 2. Common base 3. Emitter follower The correct sequence in increasing input impedance of these configuration is
(a) 2, 1, 3 (b) 1, 2, 3 (c) 1, 3, 2 (d) 3, 2, 1
Ans: A
96. The forbidden gap of a Germanium semiconductor material is
(a) 0.12 eV (b) 0.72 eV (c) 7.20 eV (d) None of these
Ans: B
97. Moving coil instruments have which one of the following scales ?
(a) Logarithmic scale (b) Uniform scale (c) Non-uniform scale (d) Squared scale Ans: B
98. P-N junction diode is used for the following application :
(a) Amplifier (b) Detector (c) Radio valve (d) None of these
Ans: B
99. The sensitivity of a voltmeter using 0-5 mA meter movement is
(a) 200 Ω/V (b) 150 Ω/V (c) 100 Ω/V (d) 50 Ω/V Ans: A
100. Which one of the following is a non-maskable interrupt ?
(a) RST 7.5 (b) RST 6.5 (c) RST 5.5 (d) TRAP
Ans: D
(a) power input – core losses (b) power input – mechanical losses
(c) Armature current × counter e.m.f. (d) Armature current × supply voltage
Ans: C
53. An electric train employing a d.c. series motor is running at a fixed speed. When a sudden drop in voltage of supply takes place, then this results in
(a) drop in speed and rise in current. (b) rise in speed and drop in current.
(c) rise in speed and rise in current. (d) drop in speed with current unaltered.
Ans: B
54. A 220 V dc shunt motor is running at 500 rpm when armature current is 50 A. The value of armature resistance is 0.2 ohm. The speed of motor at the double torque will be
(a) 250 rpm (b) 500 rpm (c) 1000 rpm (d) 476 rpm
Ans: D
55. A 10 kVA 220 V/220 V, 50 Hz transformer shows 340 W in short circuit test and 168 W in open circuit test. Its efficiency at full load and 0.8 power factor lagging is approximately
(a) 92% (b) 94% (c) 96% (d) 98%
Ans: B
56. If number of poles in lap wound d.c. generator are doubled, the generated e.m.f. will be
(a) increased by a factor of 2 (b) decreased by a factor of 2 (c) increased by a factor of 4 (d) unchanged
Ans: D
57. The material of hair spring used in measuring instruments is made of which of material of the following :
(a) Copper (b) Bronze (c) Alnico (d) None of theseAns: B
58. The most common type of prime mover used for low speed alternators is
(a) Steam turbine (b) Petrol engine (c) Hydraulic turbine (d) Diesel engine
Ans: C
59. When speed of an alternator is changed from 3600 rpm to 1800 rpm, the generated emf will be
(a) one-half (b) twice (c) one-fourth (d) four times
Ans: A
60. The power factor of an alternator is determined by its
(a) prime mover (b) speed (c) excitation (d) load
Ans: D
61. The efficiency of an ordinary transformer is maximum when
(a) it runs at half of full speed (b) it runs at full load (c) copper losses are equal to iron losses (d) it runs at slightly overload
Ans: C
62. At light load, efficiency of a transformer is low. It is because
(a) copper loss is small. (b) copper loss is high. (c) secondary output is low. (d) fixed loss is high with respect to output.
Ans: D
63. The essential condition for parallel operation of two single phase transformers is that they should have the same
(a) Polarity (b) kVA rating (c) Voltage ratio (d) Percentage impedance
Ans: A
64. A transformer transforms
(a) frequency only (b) voltage only (c) current only (d) voltage and current
Ans: D
65. Which of the following connections of a three phase transformer are best suited for 3-phase, 4-wire service ?
(a) ∆ – ∆ (b) ϒ – ϒ (c) ∆ – ϒ (d) ϒ – ∆
Ans: C
66. Transformers are rated in kVA instead of kW, because
(a) load power factor is often not known. (b) total transformer loss depends on volt-ampere.
(c) kVA is fixed where as kW depends on load power factor. (d) None of the above
Ans: B
67. A transformer has negative voltage regulation when its load power factor is
(a) Zero (b) Leading (c) Unity (d) Lagging
Ans: B
68. A 4-pole dc generator runs at 1500 rpm. The frequency of current in armature winding is
(a) zero (b) 25 Hz (c) 50 Hz (d) 100 Hz
Ans: C
69. The no load current in a transformer lags the supply voltage by
(a) 0° (b) 90° (c) 110° (d) about 75°
Ans: D
70. Two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively. The highest speed of alternators is
(a) 600 rpm (b) 500 rpm (c) 3000 rpm (d) 3600 rpm
Ans: A
71. The heat run test of a transformer without its loading is performed by means of
(a) Short circuit test (b) Open circuit test (c) Half time short circuit test and half time open circuit test (d) Sumpner’s test
Ans: D
73. A d.c. series motor should never be started at
(a) normal load condition. (b) full load condition. (c) no load condition. (d) slightly overload condition.
Ans: C
74. In a d.c. generator, 8 parallel paths and 16 brushes for collection of current are used. If voltage drop per brush is 1 V, then reduction in the induced e.m.f. will be
(a) 2 V (b) 4 V (c) 8 V (d) 16 V
Ans: A
75. The input impedance of a common base transistor is
(a) Medium (b) Low (c) High (d) Infinity
Ans: B
76. Transistor can be operated in
(a) active region only (b) cut-off region only (c) saturation region only (d) All of the above
Ans: D
78. For any inverting amplifier, the input capacitance due to Miller effect
(a) increases (b) decreases (c) remains constant (d) None of these
Ans: A
79. In an amplifier, if voltage shunt negative feedback is employed, then
(a) the bandwidth decreases (b) the output resistance decreases (c) the input resistance decreases (d) the gain increases
Ans: B
80. Feedback in an amplifier is used to
(a) control output (b) increase gain (c) decrease input resistance (d) stabilize gain
Ans: A
81. In which material, valence electrons are tightly bounded to their parent atoms ?
(a) Conductor (b) Semiconductor (c) Insulator (d) Magnetic Ans: C
82. The disc of domestic supply energy meter is made of which material ?
(a) Zinc (b) Copper (c) Aluminium (d) Silver Ans: C
83. When used as a voltage regulator, a zener diode is normally
(a) forward biased (b) reversed biased (c) not biased (d) None of the above
Ans: B
84. Ferrites are types of
(a) magnetic material (b) conducting material (c) semiconducting material (d) insulating material Ans: A
85. In a single stage amplifier D.C and A.C load lines
(a) are always parallel (b) are perpendicular to each other
(c) cross each other at Q-point (d) are inclined but do not cross each other
Ans: C
86. Super conducting materials can be used for
(a) ore refining. (b) magnetic levitation in high speed trains. (c) medical resonance imaging. (d) All of the above Ans: D
87. Improper biasing of a transistor circuit leads to
(a) excessive heat production in collector.(b) faulty location of load line. (c) heavy loading of emitter. (d) distortion in output signal.
Ans: D
88. When a P-N junction is reverse biased
(a) it offers high resistance (b) its depletion layer becomes narrow (c) its barrier potential decreases (d) it breaks down
Ans: A
89. The current gain of a common emitter transistor is 50. The change in emitter current for a corresponding change of 5 mA in base current will be
(a) 50 mA (b) 55 mA (c) 250 mA (d) 255 mA
Ans: D
90. If the maximum current of a half-wave rectified wave is 10 A, its r.m.s value is given by
(a) 3.10 A (b) 5.0 A (c) 6.37 A (d) 7.07 A
Ans: B
91. A common emitter amplifier is characterized by
(a) low voltage gain (b) very high output impedance (c) moderate power gain (d) signal phase reversal
Ans: D
92. The maximum rectification efficiency of a half-wave rectifier is
(a) 40.6% (b) 81.2% (c) 88.0% (d) 100%
Ans: A
93. The ripple factor of a power supply is a measure of
(a) its filter efficiency (b) its voltage regulation (c) its purity of output (d) diode rating
Ans: C
94. The power dissipation in a transistor is the product of
(a) Emitter current and emitter to base voltage. (b) Collector current and collector to base voltage.
(c) Emitter current and collector to emitter voltage. (d) None of the above
Ans: B
95. Consider the following circuit configurations : 1. Common emitter 2. Common base 3. Emitter follower The correct sequence in increasing input impedance of these configuration is
(a) 2, 1, 3 (b) 1, 2, 3 (c) 1, 3, 2 (d) 3, 2, 1
Ans: A
96. The forbidden gap of a Germanium semiconductor material is
(a) 0.12 eV (b) 0.72 eV (c) 7.20 eV (d) None of these
Ans: B
97. Moving coil instruments have which one of the following scales ?
(a) Logarithmic scale (b) Uniform scale (c) Non-uniform scale (d) Squared scale Ans: B
98. P-N junction diode is used for the following application :
(a) Amplifier (b) Detector (c) Radio valve (d) None of these
Ans: B
99. The sensitivity of a voltmeter using 0-5 mA meter movement is
(a) 200 Ω/V (b) 150 Ω/V (c) 100 Ω/V (d) 50 Ω/V Ans: A
100. Which one of the following is a non-maskable interrupt ?
(a) RST 7.5 (b) RST 6.5 (c) RST 5.5 (d) TRAP
Ans: D
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