SSC JE 2013 electrical question paper with solution

SSC previous year solved electrical papers / April 10, 2022

Ques 51.  The peak value of the output voltage of the half-wave rectifier is 100 V. The r.m.s value of the half-wave rectifier output voltage will be

  1. 100 V
  2. 50 V
  3. 70.7 V
  4. 35.35 V

Answer.2. 50V

Explanation:

RMS value of Half wave Rectifier is given as

VRms = Vm / 2

= 100 / 2

= 50 V

 

Ques 52.  The given circuit represents a

Schmitt-trigger

  1. Monostable multivibrator
  2. Astable multivibrator
  3. Schmitt trigger
  4. Bistable multivibrator

Answer.3. Schmitt trigger

Explanation:

  • A Schmitt trigger is a device (or the input portion of a device) that has separate thresholds for a rising signal and a falling signal. It is a positive feedback circuit that holds the output level till the input sig the al to the comparator is higher than the threshold.
  • The positive feedback is introduced by adding a part of the output voltage to the input voltage.

Schmitt triggerr

 

Ques 53. The input resistance of a FET is of the order of

  1. 100 Ω
  2. 10 kΩ
  3. 1 MΩ
  4. 100 MΩ

Answer.4. 100 MΩ

Explanation:

  • The field-effect transistor (FET) is a transistor that uses an electric field to control the electrical behavior of the device. FETs are also known as unipolar transistors since they involve the single-carrier-type operation.
  • FET has a high gate to main current resistance, on the order of 100 MΩ or more, thus providing a high degree of isolation between control and flow.
  • FET has a negative temperature coefficient of resistance and hence has better stability against the temperature.

 

Ques 54. In a series, R-L circuit supplied from a sinusoidal voltage source, the voltage across R and L is 3V and 4V respectively. The supply voltage is then

  1. 7 V
  2. 1 V
  3. 3.5 V
  4. 5 V

Answer.4. 5V

Explanation:

In a series R L circuit supplied from a sinusoidal voltage source voltage across R and L are 3V and 4V respectively. The supply voltage is then

 

Ques 55. If the insulation resistance of a 2m long sample of a cable is 10 MΩ, then the 8m sample of the same will have an insulation resistance of

  1. 40 MΩ
  2. 2.5 MΩ
  3. 2 MΩ
  4. 5.5 MΩ

Answer.2. 2.5 MΩ

Explanation:

Insulation resistance Ri is given as

Insulation Resistance

Where R is the radius of the cable

r is the radius of the Core

The insulation resistance varies inversely with the length

As per this question, we use only one conductor so the radius of the conductor, radius of insulation, and resistivity of the conductor is constant.

Now the formula become,

R=K/L

we put the value,

R1 x L1 = R2 x L2;

2 x 10 = R2 x 8

R2 = 2.5 MΩ

 

Ques 56.  An inductor is supplied from a sinusoidal voltage source. The magnetic field energy in the inductor changes from the peak value to the minimum value in 10 msec. The supply frequency is

  1. 50 Hz
  2. 25 Hz
  3. 1 Hz
  4. 100 Hz

Answer.2. 25 Hz

Explanation:

For a quarter part of wave pulse energy going down to the maximum value to minimum value. i,e

The magnetic field energy in the inductor changes from the peak value to the minimum value in 10 msec. 2

 

Ques 57.  Two 2000 Ω, 2-watt resistors are connected in parallel. Their combined resistance value and wattage rating are

  1. 1000 Ω, 2 watt
  2. 1000 Ω, 4 watt
  3. 2000 Ω, 4 watt
  4. 2000 Ω, 2 watt

Answer.2. 1000 Ω, 4 watt

Explanation:

When two resistance R1 and R2 are connected in parallel, the resulting resistance is  (R1 x R2) / (R1 + R2).

(2000 x 2000) / (2000 + 2000)

= 1000 Ω

The wattage of Resistor In Combination

The total wattage of a combination of resistance is always equal to the sum of the individual wattages of the resistor irrespective of whether the combination is series-connected or parallel connected. This is because the total physical size of the combination increases with the addition of the resistance.

Therefore the total wattage for the above question will be 2W + 2W = 4W

Hence the answer will be 1000 ohm and 4 watts.

 

Ques 58. We have three resistances each of values 1 Ω, 2 Ω, and 3 Ω. If all the resistances are to be connected in a circuit, how many different values of equivalent resistance are possible?

  1. Five
  2. Six
  3. Seven
  4. Eight

Answer.4. Eight

Explanation:

How many different combinations may be obtained with three resistors each having resistance R 2

 

Ques 59.  One B.O.T unit is

  1. 100 kWh
  2. 10 kWh
  3. 1 kWh
  4. 0.1 kWh

Answer.3. 1 kWh

Explanation:

Board of Trade Unit (B.O.T)

Board of Trade Unit (B.O.T) – a unit of energy equal to the work done by a power of 1000 watts operating for one hour

1 kWh = 1 BOT Unit

 

Ques 60.  An electric heater draws 1000 watts from a 250 V source. The power drawn from a 200 V source is

  1. 800 W
  2. 640 W
  3. 1000 W
  4. 1562.5 W

Answer.2. 640 W

Explanation:

The heater draws 1000W of power when connected to a 250V source.

Assume the resistance of the heating element to possess a value R.

Then, the power drawn by the heater Power is given by

P = V2/ R

Assuming the value of resistance to be constant

P ∝ V2

Thus,

An electric heater draws 1000 watts from a 250 V source. The power drawn from 200 V source is

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