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The Challenge: Recharge a Battery

How do we charge a battery without wall current?

We can make electricity by constructing a basic generator. This would allow us to change kinetic energy into electrical energy, which in turn could be stored as chemical energy in the battery.

The simplest generator consists of a coil of wire and a bar magnet. When you push the magnet through the middle of the coil, an electric current is produced in the wire as electrons are forced along it. This method of generating electricity is called induction.

The amount of electricity can be increased by coiling the wire around an armature to concentrate the magnetic field. The armature can then be turned in such a way that many lengths of wire keep passing through the magnetic field. The voltage can be raised by increasing the number of 'windings' of the coil, increasing the strength of the magnetic field or increasing the speed at which the generator turns.