Wireless remote control devices for television sets and video cassette recorders use invisible beams of infrared radiation (IR) as the means of transferring the information from the device in the hand of the viewer to the controls within the sets.
Try these experiments.
A. Measure the “cone” or area of infrared energy by putting the remote control device on a sheet of paper taped to a table. Move the table slowly away (and then closer) from the television. Mark the position where the device begins to work.
B. Even though you can’t see it, the beam of infrared light will reflect off a wall or the ceiling just as a beam of visible light will reflect off a mirror. Try controlling your TV set by “bouncing” the beam around the room, instead of pointing it directly at the TV.