Definition Of 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. 

Definition of 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