# Power

## Definition of Power

"The rate at which the energy is used or produced is called power."

OR The energy used or produced in a second is called power.

The energy used by an electric heater of power rating 12 watt is 12 J in a second.

OR The energy used or produced in a second is called power.

#### More About Power

- Power is energy per unit time.
- The SI unit of power is Watt.
- One watt is one joule per second.
- The average power P avg = ∆E/∆t
- The unit of power watt is named after the famous English engineer James Watt.
- 100 watt is called kilowatt and 1000000 (106) watt is called megawatt.

**Example 1:**A crane lifted a body in three seconds by spending an energy of 1500J. Then the power of crane is 500 watt.**Reason:**Power = Energy/time=1500/3=500 watt.0#### Examples of Power

The power of a generator which generates 1 joule energy in 1 sec is 1 watt.The energy used by an electric heater of power rating 12 watt is 12 J in a second.

#### Solved Example on Power:

An electric heater generates 12j energy in 2 seconds, and then the power is-
E. 1 Watt

F. 3 Watt

G. 6 Watt

H. 12 Watt

**Correct answer is C.**

#### Solution :

**Step 1:**Write down the equation for power. P = E / t

**Step 2:**Insert the value of the energy and time in Joule and seconds = 12 / 2

**Step 3:**Write down the final answer in Watt.

**Step 4:**P=6 watt.

**Related Terms**: Energy | Work
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