Interrelation Between P, V, I and R
ELECTRIC POWER: Rate of consumption of energy.
SI unit of electric power is watt (W).
P = VI
or P = I2R = `("V"^2)/"R"`
It is the power consumed by a device that carries 1 A of current when operated at a potential difference of 1 V.
Therefore: 1 W = 1 volt × 1 ampere = 1 V A
-The unit ‘watt’ is very small. Therefore, in actual practice we use a much larger unit called ‘kilowatt’.
-It is equal to 1000 watts. Since electrical energy is the product of power and time, the unit of electric energy is, therefore, watt hour (W h).
-One watt hour is the energy consumed when 1 watt of power is used for 1 hour. The commercial unit of electric energy is kilowatt hour (kW h), commonly known as ‘unit’.
1 kW h = 1000 watt × 3600 second
= 3.6 × 106 watt second
= 3.6 × 106 joule (J)