practice set

SSC JE ELECTRICAL PRACTICE SET - 3

1.

The energy stored in a capacitor as a function of voltage (V) is given by

Answer/ Hint      

Answer : B

Explanation :

Energy stored in a capacitor  =  QV   CV.V   [  Q = CV]   = CV2

                             Where, Q = change stored in capacitor plate

                                              V = developed voltage across capacitor plate

                                              C = capacitor of the capacitor

2.

A 100Ω, 1 watt resistor can sustain a maximum current of

Answer/ Hint      

Answer : A

Explanation :

P = I2

 

3.

If all the three resistances of a given Delta network are 15Ω each, then all the three resistances of the equivalent star will be

Answer/ Hint      

Answer : C

Explanation :

Equivalent star resistance of each phase  =

4.

If all the three resistances of a given star network are 10 each, then all the three resistances of the equivalent delta network

Answer/ Hint      

Answer : A

Explanation :

Equivalent delta resistance of each phase   = 

                           Where, R1 , R2 and R3 all are three star resistances and R1 = R2 = R3 = 10 Ω

                             Equivalent delta resistance  =    =  30 Ω

5.

An electrical network with seven independent branches and five independent nodes excluding the reference node should preferably be solved by

Answer/ Hint      

Answer : A

Explanation :

For mesh current analysis, no. of independent  mesh  or loop equations m are 

                              m  = b – n + 1

                              Where, b = no. of branches 

                                             n   = no. of nodes

                              m = 7 -5 + 1  =  3

6.

Most commonly employed trivalent impurities are

Answer/ Hint      

Answer : A

Explanation :

Trivalent impurity (such as Boron, indium) has three valance electrons in their outermost shell, it is also known as p-type impurities in the case of transistor action.

7.

Most commonly employed pentavalent  impurities are

Answer/ Hint      

Answer : D

Explanation :

pentavalent impurity (such as Arsenic, Antimony) has five valance electrons in their outermost shell, it releases electrons into the material in which it is added so it is also known as n-type impurities in the transistor action

8.

An N-type semiconductor as a whole is

Answer/ Hint      

Answer : A

Explanation :

An n-type semiconductor as a whole is ordinary metal like copper so it is basically electrically neutral as a whole material in which conduction takes place by application of potential difference

9.

Which of the following is the dimensional formula for conductivity

Answer/ Hint      

Answer : A

Explanation :

10.

Which of the following is the  CORRECT  expression for the capacitance of a parallel plate capacitor

Answer/ Hint      

Answer : A

Explanation :

11.

In a series combination of several inductors, the equivalent inductance is  ________ .

Answer/ Hint      

Answer : D

Explanation :

12.

Which of the following is the reciprocal of resistivity

Answer/ Hint      

Answer : C

Explanation :

13.

Determine the value of equivalent inductance, if 4 inductors having inductance  L  are connected in parallel

Answer/ Hint      

Answer : B

Explanation :

14.

Determine the conductance (in Siemens) of a conductor, when the potential difference between the ends of the conductor is  30 V and the current flowing through the conductor is 3A

Answer/ Hint      

Answer : A

Explanation :

15.

How much power (in W) will be dissipated by a 10 ohms resistor, when the current through the resistor is  3 A

Answer/ Hint      

Answer : D

Explanation :

16.

Determine the value of resistance (in ohms)  of a resistor at 40 degree Celsius, when the resistance has a resistance of  10 Ohms  at  0 degree Celsius and the temperature coefficient at  0 degree Celsius is  0.04

Answer/ Hint      

Answer : D

Explanation :

17.

Determine the energy stored (in J)  by a  5 H inductor, when the current flowing through the inductor is  6 A>

Answer/ Hint      

Answer : B

Explanation :

18.

Determine the equivalent resistance (in Ohms) for the circuit given below  Figure

           

Answer/ Hint      

Answer : B

Explanation :

19.

Determine the resistance (in Ohms) of resistor when the potential difference between the ends of the resistor is 24 V  and the current flowing through the resistor is 3 A

Answer/ Hint      

Answer : C

Explanation :

20.

Determine the value of current I3 (in A)  for the diagram given below Figure

           

Answer/ Hint      

Answer : A

Explanation :

21.

Which of the following statement is TRUE 

Answer/ Hint      

Answer : B

Explanation :

22.

Determine the  Norton’s resistance  (in Ohms) between terminal  A and B for the circuit given below Figure

Answer/ Hint      

Answer : D

Explanation :

23.

Determine the value of current  I (in A)  drawn from the voltage source for the circuit given below Figure 

Answer/ Hint      

Answer : C

Explanation :

24.

Determine the value of source resistance (in Ohms) for transmitting maximum power from the source to the load, when the load impedance of the circuit is  10 – j2 Ohms

Answer/ Hint      

Answer : B

Explanation :

25.

Determine the power (in W) delivered from the source for the circuit given below Figure

Answer/ Hint      

Answer : A

Explanation :

26.

Determine the value of Thevenin’s equivalent resistance (in Ohms) across terminal  A and B  for the electrical circuit given below Figure 

Answer/ Hint      

Answer : B

Explanation :

27.

Determine the value of load resistance (in ohms) for a circuit, when the maximum power transferred from the source of  50 V  to the load is  25 W

Answer/ Hint      

Answer : D

Explanation :

28.

What will happen to the inductance, if number of turns of the coil is decreased

Answer/ Hint      

Answer : B

Explanation :

29.

If the area of cross-section is reduced to half of its original value, then what will happen to the flux density

Answer/ Hint      

Answer : A

Explanation :

30.

Calculate the value of flux leakage coefficient, if  𝛷g is the air gap flux and 𝛷a is the flux in iron core

Answer/ Hint      

Answer : A

Explanation :

31.

The graph shown represents the  B-H curve for  ________ Figure

Answer/ Hint      

Answer : D

Explanation :

32.

A conductor of length  0.6 m is situated at the right angle to a  uniform magnetic field of flux density  4 Wb/sq. m. The conductor is moving with a velocity of 50 m/s. calculate the emf induced (in V) n the conductor

Answer/ Hint      

Answer : D

Explanation :

33.

A  600-turn coil has a resistance of  7 ohms and an inductance of  0.8 H. if one-fifith of the turns are removed, then determine the new inductance  (in H).

Answer/ Hint      

Answer : A

Explanation :

34.

A magnetic circuit of reluctance  3000 A-turns/Wb is wounded by a wire of  400 turns. Determine the average emf induced (in V)  in the coil, if a current of  2 A  is flowing in the coil is reversed in  15 s

Answer/ Hint      

Answer : A

Explanation :

35.

For the figure shown below, the permeability in the core is  4 × 10- 4 Wb/A-turns-m. what is the value of flux density (in T) in the core Figure

Answer/ Hint      

Answer : B

Explanation :

36.

Which of the following represents the quality factor of a series  RLC  circuit

Answer/ Hint      

Answer : A

Explanation :

37.

Which of the following represents the relation between the peak value and  RMS  value of voltage for a sine wave 

Answer/ Hint      

Answer : D

Explanation :

38.

Determine the average value of an alternating current (in A)  when the peak value of the current is  10 A

Answer/ Hint      

Answer : C

Explanation :

39.

What will be the frequency (in Hz) of a sinusoidal waveform, when the time period of the wave is  25 ms

Answer/ Hint      

Answer : A

Explanation :

40.

Determine the total impedance (in ohms)  of a series  RLC  circuit having a resistance of  10 Ohms, capacitive reactance of  2 ohms  and inductive reactance of  6 ohms,  connected in a series across a  200 V,  50 Hz supply

Answer/ Hint      

Answer : B

Explanation :

41.

Determine the value of phase current (in A) for a balanced delta connected system, when the value of line current is  8.7 A.

Answer/ Hint      

Answer : D

Explanation :

42.

What will be the value of inductance (in mH)  connected in parallel with a capacitance of 4 F in a series  RLC  circuit having a quality factor 2, when the resonant frequency is  6 rad/sec

Answer/ Hint      

Answer : B

Explanation :

43.

What will be the value of average power  (in W), if a sinusoidal voltage applied across a series  RC circuit is  20 sin V and the current flowing in the circuit is  10sin ( + 60) A

Answer/ Hint      

Answer : A

Explanation :

44.

Determine the total power (in kW)  consumed by a 3-phase delta connected system supplied by a line voltage of  230 V, if the value of phase current is  30 A  and the current lags the voltage by  30 degree.

Answer/ Hint      

Answer : D

Explanation :

45.

Which of the following bridge is most suitable for the measurement of an unknown resistance

Answer/ Hint      

Answer : D

Explanation :

46.

Which of the following instrument is used for the measurement of Insulation resistance

Answer/ Hint      

Answer : A

Explanation :

47.

What will be the deflection (in rad)  of a moving iron instrument, when the inductance of the moving iron instrument is  (20 +4θ) μH, where θ is the deflection in redian from zero position and the deflection current is  5 A  ? Assuming spring constant k  =  10 × 10- 6 Nm/rad

Answer/ Hint      

Answer : A

Explanation :

48.

Determine the value of the unknown capacitance  Cx (in μF)  for the circuit given below, when no current flows through the detector (D) Figure

Answer/ Hint      

Answer : B

Explanation :

49.

Which of the given losses are directly proportional to square of speed

Answer/ Hint      

Answer : C

Explanation :

50.

Breather is provided in a transformer to

Answer/ Hint      

Answer : C

Explanation :

51.

Armature reaction effect is more in

Answer/ Hint      

Answer : A

Explanation :

52.

A shunt generator running at  1000 rpm  generated emf of  100 V. If the speed increase to  1200 rpm, the generated emf is

Answer/ Hint      

Answer : B

Explanation :

53.

The primary and secondary windings of a transformer are

Answer/ Hint      

Answer : B

Explanation :

54.

Which of the following is not a part of transformer

Answer/ Hint      

Answer : A

Explanation :

55.

Find the number of poles required, if the frequency is  50 Hz  and speed of the motor is  500 rpm.

Answer/ Hint      

Answer : B

Explanation :

56.

In squirrel cage induction, the rotor slots are slight skew in order to reduce

Answer/ Hint      

Answer : C

Explanation :

57.

What type of operate a direct-on-line starter consists of a coil operated

Answer/ Hint      

Answer : B

Explanation :

58.

For a single phase capacitor start induction motor which of the following statements is valid

Answer/ Hint      

Answer : B

Explanation :

59.

The capacity of single phase induction motor is limited by

Answer/ Hint      

Answer : A

Explanation :

60.

The function of measurement system  is/are  ________

Answer/ Hint      

Answer : D

Explanation :

61.

Which of the following motor will give relatively high starting torque

Answer/ Hint      

Answer : B

Explanation :

62.

Transmission lines

Answer/ Hint      

Answer : A

Explanation :

63.

Maximum permissible span (in metre)  for wooden poles is

Answer/ Hint      

Answer : D

Explanation :

64.

A cable has an insulation of relative permittivity  2.  If the insulation is replaced by one of relative permittivity  4, the capacitance of the cable will become

Answer/ Hint      

Answer : C

Explanation :

65.

Which insulator is used on dead ends of medium voltage line

Answer/ Hint      

Answer : A

Explanation :

66.

Which type of fire extinguisher is to be used on electrical equipment or installation under fire

Answer/ Hint      

Answer : B

Explanation :

67.

What is the unit of luminance 

Answer/ Hint      

Answer : C

Explanation :

68.

Determine the power factor of  230V, 0.5 A, 40 W fluorescent lamp

Answer/ Hint      

Answer : A

Explanation :

69.

Which type of circuit breaker having higher rating

Answer/ Hint      

Answer : C

Explanation :

70.

The function of the commutator in  a  DC  machine  is  _________ .

Answer/ Hint      

Answer : A

Explanation :

71.

The voltage level of the single phase supply to residential consumer is

Answer/ Hint      

Answer : C

Explanation :

72.

A pin type insulator is made from

Answer/ Hint      

Answer : D

Explanation :

73.

How will you test the supply in plug point

Answer/ Hint      

Answer : D

Explanation :

74.

Power factor correction substations consists of

Answer/ Hint      

Answer : C

Explanation :

75.

Energy efficient motors generally have

Answer/ Hint      

Answer : D

Explanation :

76.

Material used for making knife switch is

Answer/ Hint      

Answer : C

Explanation :

77.

Luminous efficiency of a fluorescent tube is

Answer/ Hint      

Answer : D

Explanation :

78.

A fluorescent tube can be operated on

Answer/ Hint      

Answer : C

Explanation :

79.

Induction heating process is based on which of the following principles 

Answer/ Hint      

Answer : D

Explanation :

80.

A perfect black body is one which

Answer/ Hint      

Answer : A

Explanation :

81.

Low frequency supply is obtained by

Answer/ Hint      

Answer : C

Explanation :

82.

A lamp of  500 watts  having Mean spherical candle power  (MSCP) of  1000 is suspended  2.7  metres above the working plane. Calculate illumination directly below the lamp at the working plane

Answer/ Hint      

Answer : C

Explanation :

83.

The impurity added to extrinsic semiconductor is of the order of

Answer/ Hint      

Answer : C

Explanation :

84.

Figure represents a Figure

Answer/ Hint      

Answer : D

Explanation :

85.

In case of full wave rectifier, the ripple factor is

Answer/ Hint      

Answer : C

Explanation :

86.

An amplifier is used to obtain

Answer/ Hint      

Answer : A

Explanation :

87.

The function of the emitter bypass capacitor in  CE  amplifier is

Answer/ Hint      

Answer : A

Explanation :

88.

Synchronizing power of a synchronous machine is

Answer/ Hint      

Answer : C

Explanation :

89.

The normal starting methods that is used to start a synchronous motor is

Answer/ Hint      

Answer : D

Explanation :

90.

At what condition synchronous motor can be used as a synchronous capacitor

Answer/ Hint      

Answer : D

Explanation :

91.

Synchronous motor do not have self-starting property because

Answer/ Hint      

Answer : C

Explanation :

92.

The over-excited synchronous motor takes

Answer/ Hint      

Answer : A

Explanation :

93.

A three-phase synchronous motor will have

Answer/ Hint      

Answer : B

Explanation :

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