How can a Dam give us electriciy?

Answer 1

The dam blocks the path of a river and build a huge volume of water. The more the volume the more becomes the potential energy of the water due to the rising height of water in the dam. The water is then allowed to flow through flood gates on to huge wheels. The potential energy stored now transforms to kinetic energy that shows as the speed of gushing water. The powerful jets of water then rotate the wheel. the wheels in turn are attached to a dynamo system that produce electricity. The dynamo used in this case are large versions of the same dynamo that are used in bicycles.

Electricity thus produced is then transmitted through cables using Transformers.