Ques 101. For painful shock what is the range of electric shock current at 50 Hertz? (SSC-2015)

0-1 mA

3-5 mA

0-3 mA

5- 10 mA

Answer.2. 3-5 mA

The damage caused by electric shock depends on the current flowing through the body. 1 mA can be felt; 5 mA is painful.

Above 15 mA, a person loses muscle control, and 70 mA can be fatal.”

The amount of damage done by the electric shock depends not only on the magnitude of the current, but it also on which portions of the body that the electric current is flowing through. The reason for this is that different parts of the body have different resistances, which can lead to an increase in current.

Ques.102. What is the power consumed by the resistor of 20 ohms connected across 100-volt source? (SSC-2015)

300 W

100 W

500 W

50 W

Answer.3. 500 W

Explanation:-

Power is given as

P = V^{2}/R

P = 100 x 100/20

= 500 W

Ques.103. Thevenin’s theorem cannot be applied to (SSC-2015)

Passive circuit

Active Circuit

Nonlinear Circuit

Linear circuit

Answer.3. Nonlinear Circuit

Explanation:- Most of the time we want to analysis any circuit using mathematical equation and that can be applied only for linear circuits so before going to analyze we have to define our linear range Thevenin’s theorem also a mathematical method for the solution of a circuit

So despite all things, we can analyze the linear behavior by Thevenin theorem and can’t analysis nonlinear behavior using mathematical equations.

The superposition theorem is being used to prove Thevenin’s and because the superposition can be applied only to linear circuits we get the same result for Thevenin’s theorem.

Ques.104. Two lamps, Green (G) and Red (R) are connected in a motor circuit as shown in the fig. The conditions under which the lamps will burn are? (Supply is available at terminals A & B) (SSC-2015)

Green and red lamp burn when switch ‘S’ is closed.

Green lamp burns always, the red lamp burns only when switch ‘S’ is closed

The green lamp will not burn always, red lamp burns only when switch ‘S’ is closed.

The green lamp burns only when ‘S’ is open and red lamp burns only when ‘S’ is closed.

Answer.4. The green lamp burns only when ‘S’ is open and red lamp burns only when ‘S’ is closed.

Explanation:-

The green lamp burns only when ‘S’ is open and red lamp burns only when ‘S’ is closed

Ques.105. There are 3 lamps 40 W, 100 W, and 60 W. To realize the full rated power of the lamps they are to be connected in (SSC-2015)

Parallel Only

Series or Parallel

Series Only

Series-parallel

Answer.1. Parallel only

Explanation:-

By connecting the 3 lamps in parallel the total resistance of a parallel is less than the resistance of the smallest resistance. Hence the overall resistance is decreased.

The power dissipated in a circuit is equal to

P = V^{2}/R

So by reducing the resistance, we increase the overall power. Therefore to realize the full rated power of the lamps they are to be connected in parallel.

Ques.106. In a three-phase system, the volt-ampere rating is given by? (SSC-2015)

3 V_{L} I_{L}

V_{ph} I_{ph}

V_{L} I_{L}

√3V_{L} I_{L }cosΦ

Answer.4. √3V_{L} I_{L }cosΦ

Explanation:-

The 3-phase power is given by

P = 3VICosΦ

For star connection V_{L} = √3V

For Delta connection I_{L} = √3I

(3V_{L}I_{L}CosΦ)/√3

= √3V_{L} I_{L }cosΦ

Ques.107. A linear circuit is one whose parameters (SSC-2015)

Do not change with voltage and current

Change with change in the voltage

Change with change in the current

None of the above

Answer.1. Do not change with voltage and current

Explanation:-

A linear circuit is an electric circuit in which circuit parameters (Resistance, inductance, capacitance, waveform, frequency, etc) are constant. In other words, a circuit whose parameters are not changed with respect to Current and Voltage is called Linear Circuit.

Ques.108. The superposition theorem is used when the circuits contain (SSC-2015)

A single voltage source

Passive elements only

Active elements only

A number of voltage sources

Answer.4. A number of voltage sources

Explanation:-

The superposition theorem for electrical circuits states that for a linear system the response (voltage or current) in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone, where all the other independent sources are replaced by their internal impedances.

Ques.109. One sine wave has periods of 2 ms, another has a period of 10 ms. Which sine wave is changing at a faster rate? (SSC-2015)

All are at the same rate

Sine wave with period 2 ms

Sine wave with a period of 10 msec

sine wave with a period of 5 ms

Answer.2. Sine wave with period 2 ms

Explanation:-

Frequency is inversely proportional to the time period, therefore, a sin wave of 2ms will change at a faster rate as compared to the sine wave of 10 ms.