A flashlight that makes use of Faraday's principle of induction to charge a capacitor which then powers a blue or white LED.
You add energy to the capacitor by shaking it and you never have to worry about running out of batteries or having the bulb burn out.
Power is produced by the movement of a magnet through a coil of stationary copper wire as the flashlight is shaken. One of the best design features of this system is that there are rubber stoppers on either side of the tube. They cushion the magnet as it slides back and forth, making the shaking motion far more graceful than it would be without them.
10-15 seconds of shaking will yield 2-3 minutes of light
The flashlight can also be shaken continuously.
It is an ideal tool for camping, boating, emergency preparedness, or wilderness survival. It would be a good addition to the glove box of any car.