EE MCQ

SSC JE Electrical 2019 with solution SET-2
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The candle power of a lamp placed normal to a working plane is 60 CP. Find the distance if the illumination is 15 lux?

Candle Power of lamp = 60 CP

Illumination of lamp = 15 lux

Distance(D) = ? meters

Illumination of lamp = (candle power)/(distance)2

(D)2 = candle power/Illumination of lamp

(D)2 = 60/15 =4

D = √4

D = 2

Related Question

SSC JE Electrical 2019 with solution SET-2
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If a transformer has N1 = N2 = 1 : 1, then the transformer is a/an

The transformers which are particularly designed to provide electrical isolation between primary and secondary circuits, without a change in voltage and current level are called isolation transformers.

The turns ratio of such isolation transformers is 1:1 i.e N1 and N2. Hence, isolation transformers are also called 1:1 transformers.

The isolation transformer greatly reduces any voltage spikes that originate on the supply side before they are transferred to the load side. Some isolation transformers are built with a turns ratio of 1:1. A transformer of this type has the same input and output voltages and is used for the purpose of isolation only. The main function of the isolation transformer is to reduce the voltage spike before it reaches the load.

SSC JE Electrical 2019 with solution SET-2
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While estimating the overhead lines, if the number of poles required is 14, then what is the estimated number of earth sets required?

While estimating the overhead lines, the first and last pole is always earth connected and after every 3rd electrical pole, the fourth pole is earthed. Therefore, the approximate number of required ground set = 4

SSC JE Electrical 2019 with solution SET-2
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Observe the given figure. The maximum power to the load resistor is when Ri is =?

The maximum power transfer theorem states that the DC voltage source will deliver maximum power to the variable-load resistor only when the load resistance is equal to the source resistance. Similarly, this theorem states that the AC voltage source will deliver maximum power to the variable complex load only when the load impedance is equal to the complex conjugate of the source impedance.

Hence when Ri = RL the transfer of power will be maximum.

SSC JE Electrical 2019 with solution SET-2
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Form Factor × Peak Factor =?

Form factor: The ratio of r.m.s (or effective) value to average value is the form factor (Kf) of the Waveform. It has used in voltage generation and instrument correction factors.

Peak factor: The ratio of maximum value to the r.m.s value is the peak factor (Kp) of the waveform.

Form Factor × Peak Factor = (RMS Value / Average Value) * (Maximum Value / RMS Value) = Maximum Value / Average Value