## ELECTRIC POWER

The rate at which electrical work is done by an electrical appliance is called electric power, i.e.

Power =

P =

but, W = VIt

So P =

So P = VI watt (1)

Where, V = potential difference (in volt)

I = current (in ampere)

Therefore, P = potential difference (in volt) X current (in ampere)

Also we know that according to Ohm’s law V = I R

Putting the value of I in equation (1), we get

P = IR X I

or P = I^{2}R

The S.I.unit of power is** watt**. It is denoted by the letter **W**.

**1Watt**

The power is said to be of 1 watt if 1 joule of work is done in 1 second. Thus,

1 watt =

The S.I. unit of power represents a small amount of power and therefore it is inconvenient to use it where a large amount of power is involved. So, for commercial purposes a bigger unit of electric power called kilowatt is used.

1 kilowatt = 1000 watt

or 1 KW = 1000 W

**Test Your Understanding and Answer These Questions:**

- What is electric power?
- What is definition of 1 watt?
- What is definition of kilowatt?

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Rajan GuptaM.Sc, B.Ed. & LL.B. Teacher, Author & Innovator |
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