We know that power is the work done in a unit time.
Just like in mechanical work, power is the rate of doing work in work done by
electricity too. That is, power is the work done in a unit time or the energy consumed
in a unit time.
Therefore the rate of energy consumption P by an electric appliance operated with
a voltage V and drawing a current I is given by the following equation.
Power = voltage ×current
P = VI
When the voltage, V is measured in Volts (V) and the current, I in Amperes (A) the
power, Pis given in Watts (W).
Example 1
When a filament bulb is connected across a voltage difference of 12 V, a current of
2 A flows through it. What is the power of the bulb?
Power P= VI
= 12× 2 W
P= 24 W
Power of the bulb is 24 W.
