Change kinetic energy from your hand into light energy. This hand-held "dynamo" is completely visible. It clearly demonstrates how electrical energy can be produced by moving an electrical conductor through a magnetic field -- a discovery made by Michael Faraday in 1831.No batteries are required - no bulbs to replace. This is a great safety item. Place one in your car, next to your bed or in your tool box and you will always have light when you need it without the worry of discovering dead batteries!