Question

By which source is the mechanical energy produced in the generator?

Answer 1

@Priths can you please explain in detail about your question. Generator actually converts mechanical energy into electrical energy by using a principle called electromagnetic induction. Did you mean what is the source for the availability of this mechanical energy.

Answer 2

There may be several ways
In dams water falling from height rotates the dynamo connected to the coil.
Steam may be used as in case of thermal power plants

Answer 3

wind is used in the case of wind mills.