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Power is the rate of doing work or in other words, it is the work done in one second.
If a current of 'I' amperes flows through a conductor of resistance 'R' ohm for a time 't' seconds when the potential difference across its ends is 'V' volt, then the electric power consumed
P= 
P=
Using Ohm's law, 'Power' can also be expressed as
P=I2R
Or P=
The unit of power is 'watt'.
 1 watt = 
Thus if a potential difference of 1 volt causes a current of 1 ampere to flow through a wire, the electric power consumed by the wire is 1 watt.
The SI unit of electric power is watt (W). It is the power consumed by a device that carries 1 A of current when operated at a potential difference of 1 V. Thus,
1 W = 1 volt x 1 ampere = 1 V A
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