Wind turbine
How it works
When the propeller of the wind turbine is rotated the bar magnet also gets rotated. The rotation of the bar magnet over the coil of copper wire generates electricity which is stored in the coil. The bar magnet and the coil together work as a generator. The generated current passes into the diode which lets the current flow in a single direction so that the positive and the negative terminals can be separated. A galvanometer is connected to the ends of the wire. As the current passes into it, the flow of electricity is indicated by the dial. However the electricity produced is so small that the dial flickers slightly. If the propeller had moved at the speed of a table fan then the dial would clearly indicate the flow of electricity.