New LED Lights Save Energy and Last Longer

Forrest M. Mims III

Do you have an LED flashlight yet?

If not, you need to learn about these fabulous lights that are taking over where Edison and the electric lamp left off.

LED means light-emitting diode. An LED light is a tiny crystal that emits a narrow range of wavelengths when connected to a small battery.

White light can be produced by closely spaced blue, green and red LEDs. A simpler and more economical approach is to coat a blue LED with a phosphor that emits green and red wavelengths when stimulated by blue light. The result is a bright white light.

The first time I saw an LED light was in the spring of 1966 when I was a senior at Texas A&M University. I was so intrigued by these new kinds of light sources that I hitchhiked to Texas Instruments just north of Dallas to see one.

At Texas Instruments, Dr. Edwin Bonin opened a desk drawer and pulled out a small penlight battery. A small gold-colored thing with a plastic lens was attached to the top of the battery. When Dr. Bonin pressed a switch, the lens of the gold object emitted a soft red glow.

The electric lamp that Edison invented requires that a filament of thin metal be heated so hot that it glows. The LED that Dr. Bonin showed me was not heated at all. Yet it produced light directly from a crystal!

For a decade or more, LED lights were used to form numbers in the readouts of clocks and pocket calculators. Today they are often used to indicate when electrical power is applied to various appliances.

Today’s LEDs are incredibly more powerful than earlier LEDs and, especially, the primitive red one that Dr. Bonin showed me four decades ago. Many are so bright that users must avoid looking directly at them when they are operating!

New traffic lights use arrays of dozens of LEDs to produce red, amber and green light. The tail lights of most new cars use LEDs.

Some new cameras even feature bright LEDs that light up nearby objects when more light is needed for a photograph.

Because LEDs produce light so efficiently, they consume much less battery power than traditional light bulbs. In fact, one of my LED lights has used the same batteries for more than a year with no sign of weakening.

Variety stores and stores that sell hardware and sporting goods sell many different kinds of LED flashlights. They might cost a few dollars more than old-fashioned flashlights, but the LED will never need replacing and the batteries will last much longer.

Forrest M. Mims III and his science are featured online at www.forrestmims.org and www.sunandsky.org/.