Johnny B. English Sr.
SFTY 355 - Industrial Hygiene and Toxicology
May 29, 2013
Thermal radiation also known as infrared which is a form of light that can not be seen, we can only see visible light. Infrared gives us information that we would not be able to get from visible light. Because all object gives off some type of heat, yes, all objects even if the of cold or frozen. Cold or frozen objects only gives off a very small amount of heat, but this heat can be detected by infrared. We can you use infrared to gather information about the heat and temperature an object has. Anything that has a temperature whether it is cold or hot will give off will give off infrared light or heat. When looking at these objects the hotter they are the brighter they are. The less bright they appear they cooler the object is. For example if you used infrared to look at a cold or frozen object you would notice the object does not appear bright at all, but the further away from that object you move it will start to get brighter because the area is warmer than the object. The opposite is true for a hotter object the further you move from the heat the less bright the area appears. It was discovered in an 1800 experiment by William Herschel, the same astronomer that discovered Uranus. He used a cut-glass object to separate the sunlight into a spectrum of colors. While taking the temperature of the visual colors, he noticed when he placed the thermometer bulb just beyond the red colors the temperature would raise, this was the birth of thermal radiation. There are types of radiations in the electromagnetic spectrum, a lot of which we can not see. The little portion that we can see is called light. This spectrum is identified by either short or long wavelength, infrared is non-ionizing radiation found in the long wavelength between microwaves and visible light. “Infrared radiation (IR) has wavelengths ranging from 780 nm to 1 mm. Following the classification...
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