Can you imagine life without a TV remote- control? Terrible! But believe it or not, prior to the 1970s most television-sets did not have remote controls. In order to change the channel, a person had to stand up, walk to the TV-set, and manually turn the knob.
Things Required:
TV with a remote control
Mirror
Directions:
Switch on the television-set. Now use your remote control device to change channels. Determine how far away from the TV-set the remote can control it. Place a sheet of paper between the remote and the television-set. Does the remote still work or does the paper block the signal?
Stand about 10 feet from the television-set. Aim the remote at the side of the TV-set. How far away from the TV-set can the remote be aimed before it no longer switches channels?
Can the beam bounce off the ceiling and still reach the TV-set? Try reflecting the beam off the ceiling and the wall. Will the beam be reflected off or absorbed by these surfaces?
Place a mirror on the floor about midway between you and the television-set. Hold the remote at the same height as the remote receiver on the television-set. Aim the beam at the mirror. What happens? Can you explain your observation?
This Is What Happens:
Although the remote control doesn’t use visible light, it uses a similar form of energy called infrared light. Infrared, also called IR, has many of the properties of visible light. Like the colours we see, IR can bounce off mirrored surfaces. That’s why the beam that struck the mirror changed the channel. Like visible light, it was reflected from the surface and travelled along a path that ended at the TV remote receiver.
