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
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