Question { FCC, 3464 }

we have provided 30 mA rccb to water cooler.but we feel shock in cooler body.what is the reason?

Answer

Minimum magnitude of current to feel shock is just 1mA(in case of AC).
when you are not earthing equipment properly you will get shock.

Question { Sanima Hydro Power, 2997 }

Why the pointer of earthing of 3 pin top is made thick and long compared to the phase and neutral pin ?

Answer

earthing of 3 pin top is made thick and long compared to the phase and neutral pin because resistance of a conductor depends on its length and area.
R=(roh*l/A).
as resistance is inversely proportional to its area,to make low resistance path area should be more.So because to flow earthing current easily pin is made thick and long.

Question { IMD, 4302 }

How to check it good or bad capacitor

Answer

Firstly check out the rating of capacitor you want to check.According to voltage rating given on capacitor, apply the voltage to its two terminals(Note :Do not apply the voltage more than rating voltage,otherwise it will make a short circuit,less voltage can be applied) and then short those terminals.if spark between terminals is observed it is good otherwise it is bad.

Question { GATE, 3448 }

what is the calculation of power factor?

Answer

The power factor is the ratio of the real power that is used to do work and the apparent power that is supplied to the circuit. Power factor values are between 0 to 1.