EE MCQ

SSC JE Electrical 2019 with solution SET-1
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Find the net capacitance of the combination in which ten capacitors of 10 μF are connected in parallel

When the capacitance is connected in series the total capacitance is given by

Ceq = C1 + C2 + C3………CN

Ceq = 10n

Ceq =10 × 10 = 100 μF

Related Question

SSC JE Electrical 2019 with solution SET-1
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In a single-phase capacitor start-and-run motor, the minimum number of capacitors to be used in it is:

Capacitor start and capacitor run motor: Two capacitors are used for starting, but one of them is cut out when speed reaches 70 percent of the synchronous speed. The capacitor start-and-run motor starts with a high value and a low-value capacitor connected in parallel with each other but in series with the starting winding. This provides a very high starting torque. The centrifugal switch disconnects the high-value capacitor at 80 percent speed, but the lower value capacitor remains in the circuit.

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.

SSC JE Electrical 2019 with solution SET-1
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The ratio of conductor voltage and the voltage across the disc nearest to the conductor multiplied by the number discs are

The non -uniformity in the voltage distribution over a string of suspension insulators is expressed in terms of a parameter called “string efficiency“.

The voltage across the unit nearer to the conductor is more than the voltage in the unit nearer to the support. This unequal potential distribution over the string is expressed in terms of string efficiency.

The efficiency of a string is defined as the ratio of voltage across the whole string to the product of the number of discs and the voltage across the disc nearest to the line conductor. Mathematically, it can be expressed as,

Where n = Number of the unit in the string

The more the value of the string efficiency, the more uniform is the voltage distribution across the string. For the ideal case, the string efficiency is 100% and the voltage across each disc of the string is equal. Practically various methods are used to obtain string efficiency as high as possible.

SSC JE Electrical 2019 with solution SET-1
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Lamp efficiency is measured in

The luminous efficiency of an electric lamp is the ratio of the luminous flux (in lumen) emitted by the lamp to the electric power (watt) given to it i.e.

Luminous efficiency η = Luminous flux/Watt

Note:- Lumens is the unit of measurement for luminous flux, which is the total amount of visible light emitted by a source.

1

In the synchronous motor, the stator and rotor rotate at the same speed.