SSC JE 2014 Electrical question paper with solution(Evening-shift)

SSC previous year solved electrical papers / April 9, 2022

Ques 31. For the circuit shown in the figure, the voltage across the capacitor during the steady-state condition is

Numerical31

  1. 0 V
  2. 4 V
  3. 6 V
  4. 12 V✔
In steady-state condition, the voltage across the capacitor equals the voltage of the charging source i.e 12 V

 

Ques 32. A current of 5 mA flows in a resistance less choke from a 200 V alternating source. The energy consumed in the choke is

  1. 0 J✔
  2. 4.4 J
  3. 500 J
  4. 1000 J
As the choke is resistance less therefore

R = 0

Energy consumed = I2R = I20 = 0

 

Ques 33.  Find RAB for the circuit shown in the figure

Numerical33

  1. 18Ω✔
  2. 30Ω
  3. 45Ω
  4. 68Ω

When balanced, the Wheatstone bridge can be analysed simply as two series strings in parallel, therefore, the current through the 50Ω resistor is zero. Hence the circuit become

solution33 1

RAB = 30Ω || 45Ω

= 30 x 45/ 30 + 45

= 18 Ω

 

Ques 34.  Calculate the total susceptance of the circuit as shown in the figure

Numerical34

  1. 6.67 mho
  2. 1.87 mho
  3. 0.16 mho
  4. 0.08 mho✔
The susceptance of the given circuit will be B1 + B2

where B1 =  XL/(R2L + X2L)

=  4/(32 + 42)

= 0.16 mho

B2 = Xc/(R2c + X2c)

= -10/[52 + (-102)]

= -0.08 mho

∴ susceptance = 0.16 – 0.08 = 0.08 mho

 

Ques 35. The Q-factor of a parallel resonant circuit is given by

numerical35

Answer: None of the above, wrong option since the Q-factor of the parallel resonant circuit is R√C/L

 

Ques 36.  In an R-L series circuit, the phase difference between the applied voltage and circuit current will increase if

  1. XL is increased✔
  2.  R is increased
  3. XL is decreased
  4. Supply frequency is decreased

The voltage of the inductor is directly proportional to the reactance of inductor XL when Voltage across the inductor is greater than the voltage across Resistor then under this condition XL is greater than R  and the circuit becomes inductive in nature. So the phase angle increases.

 

Ques 37. A series circuit has R = 4 Ω, XL = 12 Ω and XC = 9 Ω and is supplied with 200 V, 50 Hz Calculate the power

  1. 6400 W✔
  2. 8000 W
  3. 14,400 W
  4. 19,200 W

The Impedance of the series RLC circuit is given as

solution37

 

Ques 38. Two sinusoidal currents are given by the equations i1 = 50 sin (ωt + π/4) and i2 = 25 sin (ωt – π/6). The phase difference between them in ______ degrees.

  1. 15
  2. 30
  3. 45
  4. 75✔
Phase difference Φ = Φ1− Φ2

= π/4 −(−π/6)

= 5π/12 = 75°

 

Ques 39. The reactance of 1-farad capacitance when connected to a DC circuit is

  1. Infinite✔
  2. 1 ohm
  3. 0.5 Ohm
  4. Zero Ohm
Capacitive reactance XC = 1/2πfc

And for DC the frequency is equal to zero hence

XC = 1/2π0 = ∞

 

Ques 40. A supply voltage of 230 V, 50 Hz is fed to a residential building. Write down its equation for instantaneous value

  1. 163 sin 314.16t
  2. 230 sin 314.16t
  3. 325 sin 314.16t✔
  4. 361 sin 314.16t
The AC voltage is supplied to our home, therefore, the equation of alternating voltage E is

E = Vm sinωt

and Vm =√2Vrms

= √2 × 230 = 325.27 V

= ω = 2πf = 2 × π × 50 = 314.16

= E = 325.27 sin314.16t

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