 |
|
|
|
|
|
| Anything warm radiates infra red radiation (so it's sometimes called radiant heat), which can be detected using special infra red sensors. We are able to feel infra red but we can't see it because it's outside the visible light part of the electromagnetic spectrum. So, the radiator here could be hot or cold. |
 |
But if we point an infra red camera at the radiator, we can clearly see it's radiating infra red radiation - the hottest areas show up as white and red and the coolest areas as blue. The video clip shows the radiator must be warmer than its surroundings.
 click to see real media clip of radiator plus IR camera
A hot radiator feels warm even if you don't touch it because it is radiating infra red radiation which is absorbed by your hand, warming it up.
Infra red and visible light
|
 |
A bar radiator is extremely hot - too hot to touch. But also, some of the waves go beyond infra red into the red part of the electromagnetic spectrum. This makes the bar glow red hot. |
The filament of a light bulb is even hotter. As well as infra red waves, it radiates red, green and blue waves. These mix to make white light and the filament glows white hot.
 Another use of infra red
Security lights which automatically turn on when someone approaches use a special type of infra red detector which is photoelectric. The detector contains a semiconducting material such as silicon. When someone walks near the detector, the energy of the infra red radiation they are emitting is absorbed by the silicon and causes some of its electrons to be freed. If a potential difference is placed across the silicon, you can draw a current because of these freed electrons.
Infra red and Robot Constructor
Some of the zones your robot may be sent into contain hot hazards like fires and drums of radioactive waste. If you give your robot an infra red detector, it'll be able to detect these hazards and avoid them.
|
SENSORS radio infra red light radiation
|
|
/ 
/ 
/ 
/ 
What is infra red?
