Final answer:
In remote control terms, IR stands for infrared. It represents part of the EM spectrum that also includes radio waves and visible light. IR is used in TV remotes, requiring a direct line of sight to work effectively.
Step-by-step explanation:
In remote control terms, IR stands for infrared. This refers to the type of light that remote controls use to transmit signals to TVs and other devices.
Infrared light is part of the electromagnetic (EM) spectrum, which includes a variety of types of radiation, ranging from radio waves to gamma rays.
The correct order from lowest to highest frequency is radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. Devices that use infrared technology, like TV remotes, usually require a direct line of sight between the remote control's IR emitter and the device's IR detector.
This is because infrared cannot travel through walls and other solid objects as radio waves can. Infrared is also responsible for the radiant heat we feel, as it causes water molecules to rotate and vibrate, which is why infrared lamps, or quartz heaters, can effectively warm us.