1] It is basically a dam constructed across a river which is used to store water.

2] It consists of pipes of large diameter which carry water under pressure from the storage reservoir to the turbines, these pipes are called as pen stocks. these pipes are made of steel and reinforced concrete.

3] The wheels are fitted with turbines having different types of vanes.

4] The channel which carries water away from the turbines after the water has worked on the turbines, is known as 'Tail race'.

Hydroelectric Power Plant.