SSC JE Electrical 24 March 2021 Official Paper (Shift 1)

1.Find the approximate collector current in the given transistor circuit. (Take current gain, β = 100)

1.10 mA
2.1.25 mA
3. 1 mA
4.11.5 mA

3. For an ABCD parameter of a transmission line, which of the following is correct?

1. AB – CD = 1
2. BD – AC = 1
3. AD – BC = 1
4. AD – BC = 0

4. Synchronous impedance method of finding voltage regulation of a synchronous motor is also known as:

1.  the zero power factor method
2. the EMF method
3. the MMF method
4. the saturated synchronous reactance method

5. Starting current of a straight type repulsion motor is about ________ its full load value.

1. 3 to 4 times
2. half
3. the same as
4. 7 to 10 times

6. Which of the following motors is operated either on direct or single-phase AC supply and produces approximately the same speed and output?

1. Universal motor
2. Capacitor start and capacitor run induction motor
3. Capacitor start induction run motor
4. 1-phase series motor

7. A 6-pole, wave-wound armature has 600 conductors and is driven at 700 rpm. Determine the generated EMF in the armature if the flux per pole is 10 mWb.

1. 420 V
2. 230 V
3. 500 V
4. 210 V

8. The accuracy of D’ Arsonval movements used in common laboratory meters is about ________ of the full-scale reading.

1. 10 %
2. 0.1 %
3. 5 %
4. 1 %

9. The expected voltage value across an element is 50 V. However, a voltmeter reads it as 48 V. Calculate the percentage error in the measurement.

1. 1%
2. 2%
3. 4%
4. 3%

10. The unit of magnetic field intensity is:

1. H/m
2. AT/m
3. Wb / m²
4.  A / Wb

11. Obtain the Thevenin equivalent circuit parameters Vth and Rth for the following network.

1. Vth = 10 V, Rth = 5 Ω
2. Vth = 5 V, Rth = 5 Ω
3. Vth = 10 V, Rth = 6 Ω
4. Vth = 6 V, Rth = 5 Ω

12. A single-phase line consists of two long solid conductors, each having a radius of r metre separated by a distance of D metre. What will be capacitance between the conductor?

 1. A

2. B
3. C
4. D

13. The highest rating of Triple pole with Neutral (TPN) MCB main switches available in the local market is _______.

1. 126 A
2. 189 A
3. 289 A
4. 63 A

14. Which of the following is NOT desirable property of a good heating element?

1.  High specific resistance
2. High ductility
3. High temperature coefficient of resistance
4. High melting temperature

Explain:- 

15. In the Kando system of electrical traction, a ________ supply from the sub-station is picked up by the locomotive through the single overhead contact wire.

1. 3.3-kV, 25-Hz
2. 16-kV, 50-Hz
3. 25-kV, 25-Hz
4. 15-kV, 16(2/3)−Hz

Explain:- 

16. Thermocouple meters are AC meters that respond to the ________ of a signal.

1. Peak value
2. Instantaneous Value
3. Average Value
4. RMS Value

Explain:- 

17. For an alternating voltage or current, one cycle is equal to:

1. three alternation
2. one alternation
3. two alternation
4. four alternation

Explain:- 

18. In a DC generator, brushes are made of _______.

1. Copper
2. Aluminium
3. Carbon or Graphite
4. Laminated Steel

19. For the non-inverting amplifiers as shown, find the closed-loop voltage gain.

1. 100
2. 10
3. 101
4. 11

Explain:- 

20. Which of the following fuels has the lowest calorific value?

1. Lignite
2. Petrol
3. Diesal oil
4. Anthracite coal

Explain:- 

21. The value of inductance per conductor in a three-phase line is _______ time(s) the loop inductance for the single-phase lines.

1. 2
2. 1/2
3. 1
4. 1/3

Explain:- 

22. Find the RMS value of the given current waveform.

1. I = 12.5 A
2. I = 50/√3 A
3. I = 25 A
4. I = 25/√2 A

Explain:- 

24. The direction or polarity of dynamically induced EMF can be determined by:

1. Fleming’s right-hand rule
2. Faraday’s second law
3. Kirchhoff’s law
4. Faraday’s first law

Explain:- 

25. In which of the following lighting systems, more than 90% of the total light flux is made to fall directly on the working plane with the help of deep reflectors?

1. Direct lighting
2. Indirect lighting
3. General diffusing lighting
4. Semi-indirect lighting

Explain:- 

26. Which of the following lamps use the phenomenon of fluorescence?

1. Halogen lamps
2. Neon lamps
3. Sodium Vapour Lamp
4. Fluorescent lamps

Explain:- 

27. A hybrid VR stepping motor has 8 main poles which have been castellated to have 5 teeth each. If the rotor has 50 teeth, calculate the stepping angle.

1. 18°
2. 36°
3. 1.8°
4. 3.6°

Explain:- 

28. Which of the following fuses has the highest rating?

1. Meter board fuse
2. Pole fuse
3. Sub-circuit fuse
4. Main circuit fuse

Explain:- 

29. A transformer on no-load has a core-loss of 50 W, draws a current of 2 A and has an induced EMF of 230 V. Determine the no-load power factor and core-loss current.

1. Power factor = 0.208 lagging, core-loss current = 0.416 A
2. Power factor = 0.108 lagging, core-loss current = 0.216 A
3. Power factor = 0.108 lagging, core-loss current = 2 sin(cos-1 0.108) A
4. Power factor = 0.208 lagging, core-loss current = 2 sin(cos-1 0.208) A

Explain:- 

30. The minimum size of a copper strip to be used as an earth electrode must be:

1. 2.5 mm × 4 cm
2. 25 mm × 1.6 mm
3. 25 mm × 4 cm
4. 20 mm × 4 mm

Explain:- 

31. What will be the running speed of a 6-pole synchronous motor connected to a 3-phase, 60-Hz supply, and having rated

1. 1150 rpm
2. 1200 rpm
3. 950 rpm
4. 1000 rpm

Explain:- 

32. Which of the following terms is associated specifically with nuclear power plants only?

1. Superheater
2. Breeder reactor
3. Induced draught fan
4. Electrostatic precipitator

Explain:- 

33. Identify the device in the following symbol.

1. Zener diode
2. Varactor diode
3. Tunnel diode
4. Photo diode

Explain:- 

34. Which of the following units requires a boiler, a superheater, an economiser and an air preheater?

1. Steam generating unit
2. Coal and ash handling unit
3. Turbine and alternator unit
4. Cooling unit

Explain:- 

35. Which of the following laws states that the algebraic sum of the currents at a node at any instant is zero?

1. Kirchhoff’s Voltage Law
2. Ohm’s Law
3. Faraday’s Law
4. Kirchhoff’s Current Law

Explain:- 

36. Two coils having self-inductance of 3 H and 2 H, respectively, have mutual inductance of 2 H. They are connected in series and carry a current of 4 A. Calculate the energy of the magnetic field when the self and mutual fluxes are in the same direction.

1. 8 J
2. 72 J
3. 144 J
4. 36 J

Explain:- 

37. 1 lux = _______

1. 0.1 lumens / m2
2. 1 lumens / cm2
3. 1 lumens / m2
4. 0.1 lumens / cm2

Explain:- 

38. In a steam power plant, the value of the reheat factor is of the order of:

1. 0.5 to 1.0
2. 1.6 to 2.0
3. 1.1 to 1.5
4. 2.1 to 3.0

Explain:- 

39. For magnetically isolated coils, the value of coefficient of coupling is:

1. 0
2. 1
3. 0.5
4. 0.75

Explain:- 

40. During the short-circuit test of a synchronous machine, which of the following are accounted for in the short-circuit test loss?

i. I2R loss in the armature winding due to the flow of short-circuiting (AC) current
ii. Local core loss caused by armature leakage flux
iii. Core loss due to resultant air-gap flux.
iv. Windage and friction loss

1. (i), (ii), (iii) and (iv)
2. Only (i), (ii) and (iii)
3. Only (ii), (iii) and (iv)
4. Only (i), (ii) and (iv)

Explain:- 

41. Which of the machines given in the options has the sketched phasor diagram (a) at the time of starting and (b) at the running condition, where Ia is the current in auxiliary winding and Im is the current in main winding?

1. Single-phase, capacitor start and capacitor run induction motor
2. Single-phase, capacitor start induction motor
3. Single-phase, resistance split-phase induction motor
4. Single-phase, single-value capacitor start and run induction motor

Explain:- 

42. Usually resistances used in electronic circuitry use:

1. voltage and ohmic ratings
2. voltage and current ratings
3. ohmic and wattage ratings
4. current and wattage ratings

Explain:- 

43. A two-value capacitor-run motor starts with a ________ capacitor and runs with a ________ capacitor.

1. high; high
2. low; high
3. low; low
4. high; low

Explain:- 

44. Which of the following values of an alternating voltage or current represents the real magnitude?

1. RMS value
2. Peak value
3. Average value
4. Instantaneous value

Explain:- 

45. In a steam power plant, blow down is basically nothing but wastage of _______ from the boiler.

1. unburnt coal
2. Water
3. Flue gas
4. ash

Explain:- 

46. Which of the following torques is NOT associated with a synchronous motor?

1. Pull-in torque
2. Pull-out torque
3. Running torque
4. Breakdown torque

Explain:- 

47. The phasor diagram of a load is as follows:

1. RC load
2. Pure inductor
3. RL load or RLC with the inductive reactance more than the capacitive reactance
4. Pure capacitor

Explain:- 

48. The main and auxiliary winding impedance of a 50-Hz, capacitor-start single-phase induction motor is Zm = (3 + j3) Ω and Za = (7 + j3) Ω. Determine the value of the capacitor to be connected in series with the auxiliary winding to achieve a phase difference of 90° between the currents of the two windings at the start. 

1. 225 μF
2. 22.5 μF
3. 318 μF
4. 31.8 μF

Explain:- 

49. Zero power factor method of an alternator is used to find its

1. Armature resistance
2. Efficiency
3. Voltage Regulation
4. Synchronous impedance

Explain:- 

50. In a 3-phase induction motor, the relative speed of stator flux with respect to ______ is zero.

1. Stator winding
2. Rotor
3. Rotor flux
4. Space

Explain:- 

51. Which one of the following effects is resulted because of the size of the conductor, frequency and the specific resistance of the conducting material?

1. Thomson effect
2. Proximity effect
3. Corona effect
4. Skin effect

Explain:- 

52. Which of the following diodes is also known as a ‘voltacap’ or ‘voltage-variable capacitor diode’?

1. Varactor diode
2. Step recovery diode
3. Schottky diode
4. Gunn diode

Explain:- 

53. MCCB stands for ________

1. Miniature Current Circuit Breaker
2. Maximum Current Circuit Breaker
3. Moulded Cabinet Circuit Breaker
4. Moulded Case Circuit Breaker

Explain:- 

54. Find the equivalent resistance, Req, looking into the terminals of the following circuit as indicated.

1. 14.4 ohm
2. 12.4 ohm
3. 15.2 ohm
4. 10 ohm

Explain:- 

55. As per recommendations of Indian Standard, the maximum number of point of lights, fans and 5 A socket outlets that can be connected/accommodated in one circuit is _______.

1. 15 A
2. 20 A
3. 10 A
4. 12 A

56. Three resistors, each one with a resistance of 27 Ω, are connected in delta formation. If the delta to star conversion is performed, each resistor will be changed to _______.

1. 81 Ω
2. 9 Ω
3. 6 Ω
4. 3 Ω

Explain:- 

57. Reluctance motor is basically:

1. a DC motor
2. a servo motor
3. a DC series motor
4. a single-phase synchronous motor

Explain:- 

58. A resistance is rated for 2.5 kΩ, 1 watt. Determine its maximum voltage and current ratings.

1. 100 V, 100 mA
2. 50 V, 200 mA
3. 50 V, 200 mA
4. 50 V, 20 mA

Explain:- 

59. How many parallel paths are there in a 6-pole simplex lap-wound DC machine?

1. 3
2. 2
3. 12
4. 9

Explain:- 

60. The current and voltage in the given element are i(t) = 5e-5t A and v(t) = 10e-5t V for t ≥ 0, respectively. Both v(t) and i(t) are zero for t < 0. Find the power supplied to the element.

1. p(t) = 50e-10t W
2. p(t) = 50e-25t W
3. p(t) = 10e-5t W
4. p(t) = 50e-5t W

Explain:- 

61. The total current flowing through a parallel connection of 20 Ω and 60 Ω resistors is 40 A. What will be the current flowing through the 60 Ω resistor?

1. 15 A
2. 20 A
3. 30 A
4. 10 A

Explain:- 

62. Which of the following motors can be used for power factor correction?

1. DC series motor
2. Stepper motor
3. Synchronous motor
4. Induction motor

Explain:- 

63. Given the current i(t) and voltage v(t) of a circuit element, the power p(t) and energy w(t) are given by:

1. A
2. B
3. C
4. D

64. In the given circuit, find the current I in the 3-kΩ resistor at time t = 2 sec.

1. 4 mA
2. 2 mA
3. 4 A
4. 2 A

Explain:- 

65. In which of the following lighting schemes is 90% to 100% of total light flux thrown upward to the ceiling for diffused reflection?

1. Semi-direct lighting
2. Semi-indirect lighting
3. Indirect lighting
4. Direct lighting

Explain:- 

66. Which of the following systems is used in the secondary transmission of electric power?

1. 33-kV, three-phase, four-wire system
2. 66-kV, three-phase, four-wire system
3. 33-kV, three-phase, three-wire system
4. 110-kV, three-phase, three-wire system

Explain:- 

67. A single instrument that can measure voltage, current, resistance, diode forward voltage drop and transistor gain is

1. an ohmmeter
2. a multimeter
3. a megger
4. an ammeter

Explain:- 

68. In a single-phase, resistance split-phase motor, the phase difference between the currents in the auxiliary winding and the main winding is approximately _______.

1. 60° mechanical
2. 30° electrical
3. 60° mechanical
4. 30° electrical

Explain:- 

69. A voltage source and two resistors are connected in parallel as in the given circuit. Suppose that Vs = 150 V, R1 = 50 Ω and R2 = 25 Ω. Find the currents i1 and i2 in each resistor.

1. i1 = 3 A and i2 = 6 A
2. i1 = -3 A and i2 = 6 A
3. i1 = 3 A and i2 = -6 A
4. i1 = 6 A and i2 = 3 A

Explain:- 

70. The angular velocity of a sinusoidal voltage is given as 200π radians / second. Find the frequency.

1. 50 Hz
2. 100 Hz
3. 200 Hz
4. 150 Hz

Explain:- 

71. If the wiring in a building as a 2.4-kW load, what will be the permissible insulation resistance to earth for a 240-V system of supply?

1. 0.08 MΩ
2. 0.05 MΩ
3. 0.02 MΩ
4. 0.12 MΩ

Explain:- 

72. A series motor is best suited for driving

1. Lathes
2. Cranes and hoists
3. Shears and punches
4. Machine tools

Explain:- 

73. Lighting in restaurants and malls is an example of ________.

1. industrial load
2. domestic load
3. agriculture load
4. commercial load

Explain:- 

74. In electric arc welding, the deflection of the arc from the weld point is called:

1. arc tail
2. arc blow
3. arc suppression
4. arc loss

Explain:- 

75. A network has 8 branches and 3 independent loops. How many nodes are there in the network?

1. 6
2. 5
3. 11
4. 10

Explain:- 

76. A current carrying conductor is wrapped eight times around the jaw of a clamp-on meter that reads 50 A. What will be the actual value of the conductor current?

1. 400 A
2. 6.25 A
3. 50 A
4. 12.5 A

Explain:- 

77. CRO (Cathod Ray Oscilloscope) CANNOT be used to measure _______.

1. Frequency
2. Phase
3. Power
4. Voltage

Explain:- 

78. Which of the following connections in a three-phase transformer is called open-delta connection?

1. V-V
2. Δ-Δ
3. Δ-Y
4. Y-Y

Explain:- 

79. Choose the INCORRECT statement with respect to the use of electrical transducers.

1. The output can be indicated and recorded remotely at a distance from the sensing medium
2. Electrical amplification and attenuation can be easily done.
3. Effects of friction are minimised. 
4. Mass-inertia effects are maximised.

Explain:- 

80. Choose the correct relation between magnetic flux density (B) and magnetic field strength (H) in a material with absolute permeability as μ.

1. B = μH
2. B = μ/H
3. B = μ + H
4. B = H/μ

Explain:- 

81. A single-phase 111-V, 50-Hz supply is connected to a coil with 200 turns of a coil-core assembly as shown in the given figure. Find the magnitude of maximum flux in the core.

1. 10 mWb
2. 2.5 mWb
3. 1 mWb
4. 25 mWb

Explain:- 

82. For a series RLC circuit, the quality factor is defined as the ratio of:

1. resonance frequency to bandwidth
2. reactance to resonance frequency
3. reactance to bandwidth
4. bandwidth to resonance frequency

Explain:- 

83. NPN and PNP are types of:

1. FETs
2. Thyristors
3. Diodes
4. Transistors

Explain:- 

84.  An instrument is used to measure a quantity at different time instances, and the expected values of the quantity are to be the same; however, the measured values are different. A set of 5 measurements that were recorded at different time instances are 98, 101, 99, 100 and 102. Find the precision of the third measurement.

1. 0.95
2. 0.1
3. 0.99
4. 0.9

Explain:- 

85. A long straight circular conductor placed in air is carrying a current of 250 A. Find the magnetising force at a distance of 5 cm from the conductor.

1. A
2. B
3. C
4. D

Explain:- 

86. The impedance of a circuit placed across a 120 V, 50 Hz source is (10 + j20) Ω. Find the current through the load. 

1. (2.4 + j4.8) A
2. (4.8 – j2.4) A
3. (4.8 + j2.4) A
4. (2.4 – j4.8) A

Explain:- 

87. In an alternator, the nature of armature reaction at zero power factor leading loads is _______.

1. cross magnetizing
2. demangetizing
3. non-effective
4. magnetizing

Explain:- 

88. Which of the following is the first step of any material procurement process?

1. Demand
2. Purchase order
3. Payment settlement
4. Material inspection

Explain:- 

89. Relative permeability of a non-magnetic material is:

1. 100
2. 0
3. infinity
4. 1

Explain:- 

90. An AC source is connected to an RL series circuit. The phase of the source current, θ, with respect to the source voltage will be:

1. 90° lead
2.  -90° < θ < 0°
3. 90° lag
4. 0° < θ < 90°

Explain:- 

91. Determine the external resistor required to reduce the line voltage from 120 V to 72 V for the operation of a device. The device is rated for 120 V, 100 W.

1. 48 Ω
2. 96 Ω
3. 240 Ω
4. 144 Ω

Explain:- 

92. For a pure resistance supplied through a sinusoidal voltage, the phase difference between the voltage and current phasors will be _______.

1. 0°
2. 45°
3. 180°
4. 90°

Explain:- 

93. Consider the following statements regarding aluminium conductor steel reinforced conductors in transmission lines.
State whether these statements are true or false.
(a) It is cheaper than copper conductors of equal resistance.
(b) Corona losses are reduced in it because of the larger diameter of the conductor.(c) It has lesser mechanical strength, so it needs more support for a particular length of transmission line.

1. (a) False, (b) True, (c) False
2. (a) False, (b) True, (c) True
3. (a) True, (b) True, (c) False
4. (a) True, (b) True, (c) True

Explain:- 

94. Which one of the following is a renewable source of energy?

1. Wood
2. Petroleum
3. Wind
4. LPG

Explain:- 

95. A special case of non-inverting amplifier in which all of the output voltage is fed back to the inverting input of the op-amp is called:

1. differentiator
2. integrator
3. logarithmic amplifier
4. voltage follower

Explain:- 

96. The per unit impedance of a transformer is:

1. larger if computed from primary side than from secondary side
2. the same whether computed from primary or secondary side
3. always zero
4. always infinity

Explain:- 

97. In a steam power plant, the function of _______ is to utilise the waste heat of the flue gases for heating the feed water.

1. a boiler
2. a superheater
3. an economiser
4. a condenser

Explain:- 

98. If an alternator is operating with unity power factor load, then the effect of armature reaction on the main-field flux of an alternator will be

1. nominal
2. distortional
3. demagnetising
4. magnetising

Explain:- 

99. A hydroelectric generating plant is supplied from a reservoir of capacity 3.6 × 106 m3 at a head of 100 m. Find the total energy available in kWh if the overall efficiency is 75%

1. 63675
2. 35750
3. 735750
4. 536750

Explain:- 

100. In a factory, a three-phase, 4-kV, 400-kVA synchronous machine is installed along with other induction motors. The following are the loads on the machine:
(i) Induction motors: 500 kVA at 0.8 power factor lagging
(ii) Synchronous motor: 300 kVA at unity power factor
Determine the overall power factor of the factory load

1. 7/√58 lagging
2. 7/√58 leading
3. 9/√58 leading
4. 9/√58 lagging

Explain:-