We’re going to shine some light on some bright bits of high technology: LEDs â€” light-emitting diodes. Today on Engineering Works!
A few years ago, only scientists and engineers knew about light-emitting diodes. Now you see them everywhere — tiny flashlights, instrument lights, TV remote controls, truck and bus tail-lights, traffic lights. Even stadium TV screens – all lit up by LEDs.
LEDs are one of an array of tiny electronic devices known as semiconductors, made from silicon. Unless you’ve been living in a cave, you already know about transistors and microchips. They’re semiconductors. Normal silicon doesn’t conduct, or carry, electricity. It’s an insulator – a non-conductor. If you add tiny amounts of different stuff to silicon, it starts conducting electricity. Not a lot, but it does conduct it. Different things happen depending on what you added to the silicon. Now you’ve got a semiconductor.
The simplest semiconductors are diodes. Depending on how they’re made, some diodes carry current in one direction. Some in the other. Light-emitting diodes are like other diodes, except that when an electric current hits them, they light up instead of just carrying electricity. But unlike light bulbs, they don’t get hot. And they’re really small, about the size of your little fingernail. And for their size, light-emitting diodes are really bright. This makes them handy for all the things we were just talking about.
It’s time to light up our diode somewhere else. We’ll talk with you later.