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## ELECTRIC ENERGY

The electric energy consumed by an electrical appliance is given by the product of its power and the time for which it is used i.e.

Electrical energy    =    Power X time

or,                  E    =    P X t

The S.I. unit of electrical energy is 1 joule

1 Joule

One joule is the amount of electrical energy consumed when an electrical appliance of 1 watt power is used for one second, i.e.

1 Joule    =    1 watt   X   1 second

or     1 J    =    1 w   X   1 s

or     1 J    =    1ws

Commercial Unit of Energy: - Kilowatt Hour

One kilowatt hour is the total electrical energy consumed when an electrical appliance having a power of 1 Kilowatt is used for 1 hour. It is written as kWh in short form.

Relationship between Kilowatt Hour and joule

1 kWh    =    1 kilowatt   X   1 hour

so   1 kWh    =    (1000w)   X   (60 X 60 sec.)

= 3600000 watt seconds

or   1 kWh     =    3.6   X   106 J

1. What is electric energy?

2. What is 1 joule?

3. What is commercial unit of energy?

4. Define 1 kilowatt hour.

5. What is the relationship between kilowatt hour and joule?

Developers of Fun Science
 Rajan Gupta M.Sc, B.Ed. & LL.B. Teacher, Author & Innovator Rahul Jindal B.Tech Entrepreneur & Innovator