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.
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