Published: 26 September, 2002

Light energy can be achieved using a variety of materials

We learned that plastics are being used as lights. Can any other ordinary products be developed in the same way?

The lights that create the brilliance of a desk lamp, the glow of a traffic light, or the sparkle of a Halloween lightstick all originate in very different materials. In these examples, energy of one type (heat, electrical, or chemical) is changed into energy of another type--light.

For example, in the bulb of a desk lamp, a very fine wire, often made of a metal called tungsten, gets so hot when current runs through it that it glows. In this case, heat energy is changed into light energy.

On the other hand, a traffic signal might contain hundreds of light-emitting diodes (LEDs) -- devices made of semiconducting materials. (Silicon is the best-known semiconductor, but a very useful semiconducting material for this application is called gallium arsenide.) In this case, electrical energy is changed into light energy.

Finally, when you activate a lightstick on Halloween, you mix two liquids together inside the stick. Some of the chemical energy stored within the liquids is then changed to light energy as the two liquids react with each other.

Scientists continue to look for new materials that can be made cheaply, that produce enough light, that work long enough, and that don't get too hot in the process. Here is where it is hoped that the plastics you mentioned can make a difference!