Water from the reservoir is forced under pressure into a waterway (or pipe) known as a penstock.
From there, it is carried to a turbine, often located inside the dam structure.
Adjustable guide vanes encircling the turbine control the flow of water through it.
When they open, high-pressure water is directed onto the rotating part of the turbine, known as the runner.
The turbine runner consists of blades, a bit like the propeller on a ship. These spin rapidly as the water rushes past.
The turbine shaft turns a series of magnets inside an electric coil in the generator ‐ this, in line with Faraday’s principle, produces an electric current.