In 1866, Werner von Siemens discovered the electro-dynamic principle, which today forms the basis for our electricity generation. If you move an electric conductor, such as a wire, in a magnetic field, this creates an electric voltage in the wire. If you connect the ends, current flows. This is the principle used to create electricity in generators. In the example above, the magnetic field (red) rotates and thus creates alternating voltage in the yellow conductors.
Technicians call this a “dynamo”. This principle is utilised in the same way by both bicycles and the rotating axes of turbines in power plants.
