> How remote controls use infrared beams
How remote controls use infrared beams
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The way we love our remote controls, you'd think our living rooms were the size of Texas! It's an awfully long way to go, isn't it, to change thetelevision channel or pump up the volume on the stereo? Remote controls are a perfect indulgence for couch potatoes everywhere—but have you ever stopped to wonder how they work? How come your TV remote doesn't trigger the video? Why do you have to point it directly at the TV? And when you aim your remote at a neighbor's house, does their TV channel change too? Let's take a closer look at the mysteries of remote control!
The first thing you notice about a remote control unit is that it has no wires, so it has to send signals to whatever it's operating using electromagnetic waves. Light, x-rays, radio waves, andmicrowaves are all examples of electromagnetic waves: vibrating packets of electrical and magnetic energy that travel through the air at the speed of light. Most remote controls send signals using infrared radiation (which is a kind of invisible red light that hot objects give off and halogen hobs use to cook with), though some use radio waves instead.
If you look at the top of your remote control unit, you'll see there's a small plastic light-emitting diode (LED) where the infrared radiation comes out. Now take a look at your TV or video. Somewhere on the front, there's a very small infrared light detector. When you press the remote control, a beam of infrared radiation travels from the remote to your TV at the speed of light and the detector picks it up.
Human eyes can't detect infrared, so even if you press the buttons on your remote and stare at the LED you won't see anything happening. Some animals, including rattlesnakes, can detect infrared. Rattlesnakes have tiny infrared detectors buried in pits near their eyes, which work a bit like the infrared detectors on your TV. By homing in on infrared heat, snakes can locate prey at night when there's no ordinary light to see by. What would happen if you pointed a TV remote control at a snake and pressed the buttons? Maybe it would think you were a mouse and slither over to eat you. It's unlikely you could control a rattlesnake with a TV remote—and we don't recommend you try!