A dynamo is a machine that converts mechanical energy into electricity. The word “dynamo” comes from the Greek word for power, “dynamis”. Dynamo was originally another name for an electric generator, and still has this meaning in some languages, such as Russian. A small dynamo may be used to power a bicycle headlamp; larger ones are used in shipyards and power stations to generate electricity on a large scale.
The first machine capable of converting mechanical energy into electrical energy was developed by English scientist Michael Faraday in 1831. He called it the Dynamotor. However, it wasn’t until 1866 that French engineer Hippolyte Pixii built the first practical AC dynamo. His design used a rotating magnet inside of a coil of wire to generate an alternating current (AC).
The modern day Dynamo theory was proposed by Russian physicist Aleksandr Mikhailovich Lyapunov in 1892. This theory explains how stars generate their magnetic fields via a process known as the dynamo effect. In essence, the motion of electrically conducting fluids within celestial bodies creates electric currents which in turn produce magnetic fields.
Lyapunov’s work on the Dynamo theory was later extended by other scientists, including Harold Jeffreys and Arthur Eddington who applied it to explain the Earth’s magnetic field