What Is Work, Power, and Energy
Work
When a force is applied to a body causing it to move, and if a displacement, d is caused in the direction of the force, then
If force is in Newtons and d is in meters, then work done is expressed in Newton–meter which is called Joules.
Power
Power is the rate at which work is done, i.e., rate of doing work. Thus,
The unit of power is Joules/second which is also called Watt. When the amount of power is more, it is expressed in Kilowatt, i.e., kW.
1 kW = 1 × 103 W
We have earlier seen in eq. (1.3), that electrical potential, V is expressed as
Thus in a circuit if I is the current flowing, and V is the applied voltage across the terminals, power, P is expressed as
Thus electrical power can be expressed as
Energy
Energy is defined as the capacity for doing work. The total work done in an electrical circuit is called electrical energy. When a voltage, V is applied, the charge, Q will flow so that
If power is in kW and time is in hour, the unit of energy will be in Kilowatt hour or kWh.
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