SSC Junior Engineer Electrical Online Exam 2018 CPWD/CWC/MES Electrical Engineering 23-01-2018 Morning

1. How much time (in sec) will be taken by 40 C of charge to pass through a point in a circuit, if a current of 8 A flows through it ?

A) 2
B) 3
C) 4
D) 5

... Answer is D)
Electric Current Formula and Unit
If a charge Q flows through the cross-section of a conductor in time t, the current I then I=Q/t. The S.I unit of charge is coulomb and measurement of electric current happens in units of coulomb per second which is 'ampere'.

I = Q/t

8 = 40/t

t = 40/8 = 5 sec.

2. Four capactiors of 15 mF are connected in parallel. What is the equivalent capacitance (in mF) of the combination ?

A) 60
B) 65
C) 70
D) 75

... Answer is A)
Given : C1 = C2 = C3 = C4 = 15 mF

Since C1,C2,C3,C4 are in parallel combination

So, equivalent capacitance = C1 + C2 + C3 + C4 = 15 + 15 + 15 + 15 = 60 mF

3. At 20 degree Celsius, aluminium wire has a resistance of 30 ohms. The temperature coefficient of resistance is 0.00305 per degree Celsius. What is the approximate resistance of the wire (in ohms) at 30 degree Celsius ?

A) 28 Ω
B) 31 Ω
C) 35 Ω
D) 45 Ω

... Answer is B)
Given that, Rref = 30 Ω, α = 0.00305/°C, Tref = 20°C, T = 30°C

RT′=RT*[1+α(T′−T)]
= 30*[1+.00305(30−20)]
= 30*[1.0305]
= 30.92 Ω = lamsum 31 Ω

4. On which supply does the appliances based on heating effect of electric current work ?

A) AC
B) DC
C) Both AC and DC
D) None of these

... Answer is C)
Through a pure resistance, AC and DC have the same heating effect. In fact, an effective description of “the RMS voltage” for an AC voltage is that voltages which produces the same heating as the same voltage of DC. ... Through a pure resistance, AC and DC have the same effect.

Electrical appliances which work on heating effect of electric current Domestic appliances based on the heating effect of electric current:

Electric Iron.
Electric heater.
Electric geyser.
Induction Cooker.
Microwave Oven.
Hair blower.

5. Find the resistivity of a material (in Ohms–cm) of wire whose resistance is 5 ohms. (Assume length of the wire is 15 m, diameter of wire is 0.15cm ?

A) 5.87 × $10^–5$
B) 5.87 × $10^–7$
C) 7.87 × $10^–5$
D) 7.87 × $10^–7$

... Answer is A)

6. The two metal plates having an area of 50 sq. m are separated by a dielectric material having thickness of 4 mm and relative Permittivity of 9. Calculate the capacitance (in micro–Farad) across the metal plates ?

A) 0.5
B) 0.996
C) 1.76
D) 2.1

... Answer is B)
Area of plate d = 50 sq.meter

relative Permittivity εr = 9

capacitance of capacitor c = ε0εr A/d

ε0 = 8.85x$10^-10$

capacitance of capacitor C = 8.85x$10^-10$ x 9 x 50 / 4 x $10^-3$


C = 995.6 x $10^-9$

C = .996 µF

7. A choke of 20 H carries a current of 600 mA. Calculate the energy stored (in J) in form of magnetic field by the choke ?

A) 0.5
B) 1.2
C) 2.5
D) 3.6

... Answer is D)
Given
Inductance (L) = 20 H
Current I = 600 x $10^-3$ Amp

the energy stored in choke E = (1/2) L$I^2$

= .5 x 20 x 600 x $10^-3$ x 600 x $10^-3$ Amp


= 3.6 J

8. Three electric lamps of 70 W each are connected in parallel across AC mains. What is the total power consumed (in W) by the parallel combination ?

A) 70
B) 140
C) 210
D) 380

... Answer is C)
The total power consumed in a parallel circuit is equal to the sum of the power consumed by the individual equipment.

Peq = P1 + P2 + P3

Peq = 70 + 70 + 70

Peq = 210 W

9. The dimensions of a cuboidal metal strip are a = 5 cm, b = 15 cm and c = 10 cm. What is the ratio of resistances Ra: Rb: Rc between the respective pairs of opposite faces ?

A) 1: 3: 5
B) 1: 3: 2
C) 1: 9: 4
D) 1: 9: 16

... Answer is C)
We know R = p L/A and cuboidal metal is same than p value is same so we can leave this for calculation of resistance

Ra = L/A = a / bxc = 5/150 = 1/30

Rb = L/A = b / axc = 15/50 = 3/10

Rc = L/A = c / bxa = 10/75 = 2/15

Ra: Rb: Rc = 1/30 : 3/10 : 2/15

Ra: Rb: Rc = 1: 9: 4

10. Calculate the equivalent capacitance (in µF) between point A and B. ?

A) 6.7
B) 8.7
C) 9.7
D) 10.7

... Answer is A)
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11. What is the efficiency (in%) of the circuit, when the maximum power is delivered to the load ?

A) 40
B) 50
C) 70
D) 80

... Answer is B)
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12. In which combination, the electrical appliances are connected at home ?

A) Series
B) Parallel
C) Series–parallel
D) None of these

... Answer is B)
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13. How many nodes and junctions are present respectively in the circuit shown below ?

A) 5, 2
B) 5, 5
C) 2, 2
D) 2, 5

... Answer is A)
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14. For the figure shown below, find the value of conductance 'G' (in S). ?

A) 3
B) 0.33
C) 6
D) 10

... Answer is B)
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15. Determine the potential difference (in V) between nodes B and D. ?

A) –5
B) 5
C) –6
D) 6

... Answer is C)
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16. The open circuit voltage across the load terminals is 30 V. The terminal voltage drops to 20 V, when the load of 15 ohms is connected across the open circuited terminals. What is the internal resistance (in ohms) of the source ?

A) 5.5
B) 6
C) 7
D) 7.5

... Answer is D)
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17. For the circuit shown below, what is the values of Thevenin's equivalent voltage (in V) across the terminals A–B ?

A) 20
B) 30
C) 40
D) 44

... Answer is B)
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18. At the maximum power transfer condition, the power transferred to the load is 70W. What is the total power (in W) generated by the voltage source ?

A) 135
B) 138
C) 140
D) 144

... Answer is C)
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19. Determine the current 'l' (in A) delivered by the source in the circuit given below ?

A) 35
B) 38
C) 42
D) 44

... Answer is D)
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20. Find the current (in mA) flowing through the load resistance RL ?

A) 5.7
B) 6.7
C) 10.7
D) 12.7

... Answer is A)
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21. Which of the following statement is TRUE about the magnetic reluctivity ?

A) Reluctivity is the reciprocal of reluctance
B) Reluctivity is the reciprocal of susceptibility
C) Reluctivity is the reciprocal of permeance
D) Reluctivity is the reciprocal of permeability

... Answer is D)
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22. Which of the following expression statisfies the Ampere's circuital law ?

A) N m
B) R K
C) A S
D) M S

... Answer is A)
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23. The ratio of total flux linkage to used flux is known as …… ?

A) flux gain factor
B) flux leakage factor
C) field gain factor
D) field leakage factor

... Answer is B)
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24. Magnetic flux per unit area is called …… ?

A) permeability
B) susceptibility
C) magnetic flux density
D) reluctivity

... Answer is C)
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25. What will be the permeance (in H) of a coil, when the flux through the coil is 50 Wb and the value of produced mmf is 25 Amp–turns ?

A) 6
B) 4
C) 3
D) 2

... Answer is D)
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26. What will be the current (in A) through a solenoid, when the solenoid has 160 turns and produces an mmf of 32 Amp–truns ?

A) 0.1
B) 0.2
C) 0.4
D) 0.8

... Answer is B)
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27. Determine the magnetic field strength (in A– turns/m) when the intensity of magnetization of the material is 0.078 A–turns/meter and the magnetic susceptibility of the material is 0.0013. ?

A) 60
B) 40
C) 50
D) 20

... Answer is A)
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28. What will be the value of coupling factor between two coils, when the self–inductance of each coil is 30 mH and the mutual inductance between them is 60 mH ?

A) 1
B) 2
C) 3
D) 6

... Answer is B)
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29. Determine the eddy current loss (in W) in a material having eddy current coefficient of 1, thickness of 0.04 m and volume of 2 cubic metre which is kept in a magnetic field having a maximum flux density of 4 T and supplied by a frequency of 50 Hz. ?

A) 140
B) 128
C) 108
D) 100

... Answer is B)
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30. What will be value of magnetic field (in mT) at the centre of a 7 m long coil, when the coil has 230 turns and carrying a current of 3 A ?

A) 0.426
B) 0.435
C) 0.265
D) 0.124

... Answer is D)
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31. Which of the following is the expression for quality factor of parallel RLC circuit ?

A) N m
B) R K
C) A S
D) M S

... Answer is ..)
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32. At resonant frequency, the impedance of the series RLC circuit is …… ?

A) purely resistive
B) purely inductive
C) purely capacitive
D) zero

... Answer is A)
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33. Which of the following represents the relation between the peak and average value of current for a sine wave ?

A) Iavg =0.707 Ip
B) Iavg =1.414 Ip
C) Iavg =0.637 Ip
D) Iavg =0.874 Ip

... Answer is c)
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34. in a parallel resonant circuit, the input impedance of the circuit is … ?

A) minimum
B) maximum
C) zero
D) infinite

... Answer is B)
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35. Determine the average value of alternating current (in A) when the peak value of current is 14 A ?

A) 8.92
B) 6.56
C) 4.26
D) 2.94

... Answer is A)
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36. What will be the total impedance (in Ohms) of a series RLC circuit, when the resistance of the circuit is 12 ohms, capacitive reatance of the circuit is 3 Ohms and the inductive reactance of the circuit is 8 Ohms connected in series with a 220 V, 50 Hz supply ?

A) 10
B) 12
C) 13
D) 15

... Answer is C)
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37. Determine the capacitive reactance (in Ohms) of a series resonant circuit, when the circuit is supplied by a frequency of 50 Hz and having a capacitance of 0.04 mF. ?

A) 65.65
B) 79.62
C) 82.26
D) 84.64

... Answer is B)
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38. What will be the resonant frequency (in kHz) of a tank circuit, when the capacitance and inductance of the circuit is 0.06 mF and 0.06 mH respectivey ?

A) 1.45
B) 1.85
C) 2.65
D) 3.25

... Answer is C)
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39. Calculate the value of capacitance (in mF) connected in parallel with a inductance of 3 H, when the resonant frequency of the circuit is 4 rad/sec ?

A) 12.63
B) 20.83
C) 18.55
D) 15.62

... Answer is B)
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40. What will be the transient time (in seconds) of a series RC circuit, when the capacitance of the circuit is 8 mF and the resistance of the circuit is 8 kilo–Ohms ?

A) 64
B) 52
C) 44
D) 36

... Answer is A)
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41. Which of the following is the CORRECT expression for the series resistance required to convert a galvanometer (having internal resistance 'G') into volmeter ?

A) V/ig - G
B) V/G - ig
C) ig/V - G
D) V/ig + G

... Answer is A)
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42. De Sauty's Bridge is most suitable for the measurement of ?

A) resistance
B) inductance
C) capacitance
D) frequency

... Answer is c)
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43. Which of the following is NOT a component of a CRO ?

A) Electron gun
B) Deflection plate system
C) Fluorescent screen
D) Motor

... Answer is D)
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44. A wattmeter is used to measure … ?

A) Only AC power
B) Only DC power
C) both AC and DC power
D) both AC and DC Voltage

... Answer is C)
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45. Determine the deflection factor (in V/m) of a CRO, when the deflection sensitivity of the CRO is 4 m/V ?

A) 0.2
B) 0.25
C) 0.35
D) 0.45

... Answer is B)
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46. Determine the value of current (in mA) for the full–scale deflection of a voltmeter, when the sensitivity of the voltmeter is 50 ohm/Volt. ?

A) 1
B) 2
C) 10
D) 20

... Answer is D)
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47. Determine the fastest rise time (in ms) of a sine wave that is reproduced by a CRO, when the bandwidth of the sine wave is 50 Hz. ?

A) 5
B) 6
C) 7
D) 3

... Answer is C)
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48. Determine the value of shunt resistance (in Ohms) required to convert a galvanometer into ammeter of reading upto 14 A, when the internal resistance of the galvanometer is 27 Ohms and the value of current for full scale deflection is 0.5 A. ?

A) 4
B) 2
C) 1
D) 0

... Answer is C)
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49. Calculate the value of unknown capacitance Cx (in µF) for the circuit given below, when no current flows through the detector (D) ?

A) 30
B) 40
C) 50
D) 60

... Answer is A)
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50. Calculate the value of reactive power (in VAR) of a circuit having power factor of 0.8, when the apparent power of the circuit is 200 VA. ?

A) 100
B) 120
C) 140
D) 160

... Answer is B)
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51. A consideration of the power losses in electrical machines is essential for which of the following reasons ?

A) Operating cost
B) Temperature rise
C) Voltage drops
D) all option are correct

... Answer is D)
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52. The flux is maximum in the following part of a dc motor ?

A) pole core
B) under the interpole
C) under leading pole up
D) under trailing pole up

... Answer is C)
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53. In DC machine torque is proportional to ?

A) flux
B) armature current
C) both flux & amature current
D) None of thse

... Answer is C)
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54. Permanent magnet excitation is also known as ?

A) shunt excitation
B) series excitation
C) separate excitation
D) compound excitation

... Answer is C)
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55. The functions of inter poles are ?

A) nullify reactance voltage
B) reduce cross magnetization effect
C) nullify reactance voltage and reduce cross magnetization effect both
D) None of these

... Answer is C)
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56. A 10 KVA auto transformer, turn ratio is 0.4. Find the power transferred inductively ?

A) 4kVA
B) 6kVA
C) 10 kVA
D) 0 kVA

... Answer is B)
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57. On Parallel operation of two or more transformers the percentage impedance of transformers should be ?

A) Such that actual impedance of all transformers would be same
B) same
C) proportionate to MVA rating of transformers
D) inversely proportional to MVA rating or transformers

... Answer is #)
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58. inversely proportional to MVA rating or transformers ?

A) Electromagnetic induction
B) Magnetic induction
C) Ferro Magnetic induction
D) Faraday's law of electromagnetic induction

... Answer is D)
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59. The principle of operation of a 3–phase induction motor is most similar to that of ?

A) synchronous motor
B) capacitor–start induction run motor
C) repulsion–start induction motor
D) transformer with a shorted secondary

... Answer is D)
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60. If the supply frequency to the stator is reduced the Induction motor goes to ?

A) increase the torque
B) Regenerative braking
C) stator magnetic breaking
D) increasing speed of rotor

... Answer is B)
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61. The direction of rotation of hysteresis motor is reversed by ?

A) Shift shaded pole with respect to main pole
B) Reversing supply lead
C) Either A or B
D) Neither A nor B

... Answer is A)
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62. If the centrifugal switch of a two–value capacitor motor using two capacitors fails to open then ?

A) motor will not come upto speed
B) motor will not carry the load
C) current drawn by the motor will be excessively high
D) electrolytic capacitor will, in all probability, suffer break down

... Answer is D)
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63. In a capacitor start single–phase motor, when capacitor is replaced by a resistance ?

A) torque will increase
B) the motor will consume less power
C) motor will run in reverse direction
D) motor will continue to run in same direction

... Answer is D)
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64. Locked rotor current of a shaded pole motor is ?

A) equal to full load current
B) less than full load current
C) slightly more than full load current
D) none of the above

... Answer is C)
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65. Theory involved in analysis of the performance of single phase induction motor is ?

A) Double field revolving theory
B) cross field theory
C) Double field revolving theory and cross field theory both
D) None of these

... Answer is C)
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66. Hysteresis motor is particularly useful for high–quality record players and tape recorders because ?

A) It revolves synchronously
B) It is not subject to any magnetic or mechanical vibrations
C) It can be easily manufactured in extremely small sizes
D) It develops hysteresis torque which is exteremely steady both in amplitude and phase

... Answer is D)
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67. For the transmission line, if booster transformers are to be used, preferred location will be ?

A) at the receiving end
B) at the sending end
C) at the intermediate point
D) anywhere is the line

... Answer is C)
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68. Wooden poles are not used because ?

A) they easily rot below the ground level and limited to line voltage of 11 kV
B) light in weight
C) can easily he fitted and shifted
D) cheap in cost

... Answer is A)
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69. Electro–mechanical voltage regulators generally find applications in ?

A) generators
B) transformers
C) reactors
D) all option are correct

... Answer is A)
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70. The material for armouring on cable is usually ?

A) galvanized steel wire
B) steel tape
C) Both galvanized steel wire and steel tape
D) None of these

... Answer is C)
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71. Towers are used in ?

A) distribution
B) transmission
C) telephone
D) street light

... Answer is B)
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72. Different types of relays are used in control circuits. They operate under predetermined conditions to full–fill the control requirement. Some relays are capable of operating with time–delay. Which one of the following is used as time delay relay ?

A) Reed relay
B) Electromagnetic relay
C) Clapper type armature relay
D) Thermal relay

... Answer is D)
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73. Bucholz relay protects the transformer from ?

A) internal faults
B) external faults
C) both internal and external faults
D) short circuit fault

... Answer is A)
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74. Insulation resistance is measured by ?

A) ohm meter
B) ammeter
C) voltmeter
D) Megger

... Answer is D)
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75. What is the meaning of sweep in case of celling fan ?

A) current rating
B) voltage rating
C) blade size
D) power rating

... Answer is C)
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76. The operation of distance relay depends upon ?

A) distance only
B) ratio of current to voltage
C) current only
D) ratio of voltage to current

... Answer is D)
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77. The underground system cannot be operated above ?

A) 440V
B) 11KV
C) 33KV
D) 66KV

... Answer is D)
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78. HRC fuse means ?

A) High resistance capacitance fuse
B) High range capacity fuse
C) High rupturing capacity fuse
D) High ratio cartridge fuse

... Answer is C)
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79. How will you change the rotation of D.C. shunt motor ?

A) change the field terminal
B) change the supply terminal
C) change the armature terminal
D) any A or C

... Answer is D)
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80. How will you convert galvanometer into ammeter ?

A) low resistance parallel with galvanometer
B) low resistance series with galvanometer
C) high resistance parallel with galvanometer
D) high resistance series with galvanometer

... Answer is A)
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81. For which of the following DC motors, is the typical field of application mentioned ?

A) Shunt motor: Electric trains
B) Series motor: Machine tools
C) Series motor: Belt drive
D) Compound motor: Fly wheel drive

... Answer is D)
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82. High pressure mercury discharge lamps are not used in ?

A) park
B) in the street lights of play grounds
C) stage lighting
D) drawing room

... Answer is D)
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83. Which of the following lamp gives nearly monochromatic light ?

A) Sodium vapour lamp
B) GLS lamp
C) Tube light
D) Mercury vapour lamp

... Answer is A)
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84. Power factor is highest in case of ?

A) Mercury arc lamp
B) Sodium vapour lamps
C) Tube lights
D) GLS lamps

... Answer is D)
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85. The process of heat transfer during the re– entry of satellites and missiles at very high speeds, into earth's atmosphere is known as… ?

A) Ablation
B) Radiation
C) Viscous disspiation
D) Irradiation

... Answer is A)
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86. A pole–changing squirrel cage induction motor employed in derricks has four, eight and twenty four pole. The lowest speed is used in ?

A) hoisting
B) landing the load
C) lifting
D) lowering

... Answer is B)
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87. In heating the ferro–magnetic materials by induction heating, heat is produced owing to ?

A) Flow of induced current through the charge
B) Hysteresis loss occurring below Curle temperature
C) Hysteresis loss as well as eddy current loss occulting in the charge
D) Any of the factors given in the options

... Answer is C)
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88. A 30 kW rated output, 400V, 3 phase delta connected, 4–pole, 50 Hz induction motor full load slip of 5%. If the ratio of standstill reactance to resistance per rotor phase is 4 estimate the full load speed ?

A) 1425 rmp
B) 1500 rmp
C) 1350 rmp
D) 1625 rmp

... Answer is A)
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89. The conduction band is ?

A) the region of free electrons
B) a range of energies corresponding to the energies of the free electrons
C) always above the forbidden energy level
D) concentrated holes for the flow of current

... Answer is A)
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90. The motor that is used for intermittent, high torque loads is ?

A) DC series motor
B) DC shunt motor
C) cumulative compound motor
D)differential compound motor

... Answer is C)
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91. IDC in a full wave rectifier is ?

A) Im/2π
B) 2Im/π
C) Im/π
D) 4Im/π

... Answer is B)
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92. The relationship between α and β factors of a transistor can be defined as ?

A) α = β/(β–1)
B) αβ=1
C) β = α/(1–α)
D) β= α /(α–1)

... Answer is C)
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93. The operating point is also called the ?

A) quiescent point
B) saturation point
C) cut–off point
D) None of these

... Answer is A)
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94. The input impedance of an amplifier is ?

A) Vinp/(Iout–Iinp)
B) Vin/Iout
C) Vin/Iin
D) Vout/Iin

... Answer is C)
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95. The speed regulation of a synchronous motor is always ?

A) 0.005
B) positive
C) 0.01
D) zero

... Answer is D)
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96. In a synchronous motor, at constant loading condition, if the excitation in increased its power factor become ?

A) more
B) less
C) constant
D) no change

... Answer is A)
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97. If excitation of a synchronous motor running with a constant is decreased from its normal value, it leads to ?

A) increase in both amature current and power factor which is lagging
B) increase in both amature current and power factor angle
C) increase in torque angle but decrease in back e.m.f.
D) increase in back e.m.f. but decrease in armature current

... Answer is B)
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98. At leading power factor the induced e.m.f. in a synchronous motor will be ?

A) equal to the supply voltage
B) less than the supply voltage
C) more than the supply voltage
D) None of these

... Answer is C)
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99. A synchronous motor can be started by ?

A) providing damper winding
B) D.C. compound motor D.C.
C) pony motor
D) any of the options

... Answer is D)
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100. In a synchronous motor, the torque angle is the angle between ?

A) magnetizing current and back e.m.f.
B) the rotating stator flux and rotor poles
C) the supply voltage and the back e.m.f.
D) None of these

... Answer is B)
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