Dynamics: Energy Exchange

A torch without a battery

Fig. 13-6: An environmentally friendly torch

Torches are normally powered by batteries. However, Fig. 13-6 shows an environmentally friendly torch which works on the principle of energy exchange.

When one shakes the torch, the strong magnet at the far right in the body of the torch (Fig. 13-6) moves and passes through electrical wires backwards and forwards and produces an electric current. Part of the kinetic energy generated by the magnet is converted to electric energy. The electric energy then changes into chemical energy through the electronic circuit and is stored in an internal storage cell. When a user switches on the torch, the chemical energy in the storage cell converts to electric energy and the electric energy changes to light energy in the bulb.