EE MCQ

SSC JE Electrical 2019 with solution SET-1
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Which of the following lamps has the shortest/less life span in working hours?

The lifespan of a bulb is referred to as “Average Rated Lifetime Hours” (ARL). Incandescent bulbs generally have the shortest lifespans. The average incandescent bulb light span is approximately 750-2,000 hours. Fluorescent lights generally have a life expectancy of 10,000 to 20,000 hours and other high-intensity lamps, such as high-pressure sodium, have greater than 20,000 hours of life expectancy.

Related Question

SSC JE Electrical 2019 with solution SET-1
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Which of the following fuel has the least calorific value?

In the above option, the wood has the lowest calorific value. Its value is around 17000 – 20000 kilojoule/kg.

The calorific value of LPG is 55000 kilojoule/kg.

The calorific value of Kerosene oil is 45000 kilojoule/kg.

The calorific value of hydrogen oil is 150000 kilojoule/kg.

SSC JE Electrical 2019 with solution SET-1
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Find the frequency of rotor induced EMF of a 3-phase, 440V, 50 Hz induction motor has a slip of 10%

Given Data

Voltage = 440 V

Frequency = 50 Hz

Slip = 10% =0.1

Now,

Rotor frequency = slip × frequency

= 0.1 × 50 = 5 Hz

SSC JE Electrical 2019 with solution SET-1
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For a three-layer stranded wire, the number of strands in the first, second, and third layer respectively are:

The total number of the conductor in stranded cable is given by

N = 3x2 − 3x + 1

Where

x = no. of layer

For layer 1

N1 = 3(1)2 − 3(1) + 1

N1 = 1

For layer 2

N2 = 3(2)2 − 3(2) + 1

N2 = 7

In layer 2 no. of conductor = N2 − N1 = 7 − 1 = 6

For layer 3

N3 = 3(3)2 − 3(3) + 1

N3 = 19

In layer 3 no. of conductor = N3 − N2 = 19 − 7 = 12

SSC JE Electrical 2019 with solution SET-1
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Identify the INCORRECT statement with regards to synchronous motors

A synchronous motor is not a self-starting motor. You can check out this article why synchronous motor is not self starting