Sunday, September 19, 2021, 00:04
Infrared radiation is part of the electromagnetic spectrum and has to do with, among other things, heat. Infrared radiation has higher wavelengths than the red color of the visible spectrum. All bodies above the absolute temperature zero shoot infrared radiation. Therefore, if we had infrared eyes, we would see in a dark room. This happens, for example, with the Python snake. It has a few eyes, only infrared sensitive, able to detect temperature variations of 0.05 ° C that are produced by a dam at a distance of 5 meters.
The discovery of infrared radiation was completely casual. In 1800, FW Herschel broke off, with a prism, sunlight in their colors and had a table influenced to measure their temperature with a Kwiktthermometer. They all had the same temperature. At the end he left the thermometer to the right of the red color. When he picked it up, he saw that he had raised the temperature in a place where the light did not arrive. His first reaction was to think that the sun rays of light and heat rays and how they appeared to the red called infrared. A few years later, Maxwell showed that these rays were of the same nature as visible light, electromagnetic waves, but of different wavelength. In the second half of the XIX there was an intense investigation into this new radiation, empirical and theoretical, a relationship (law) between thermal radiation and temperature. With this law the first calculation of the surface temperature of the sun (approximately 6000 ° C) was made. Other spectral relationships were found, but despite theoretical efforts, researchers could not explain the infrared spectrum with what we now call classical physics. It was in L900 when Planck, assuming energy is given by the sum of discreet energy units (how much) it succeeds in explaining the spectral experimental curves of infrared radiation. With this work, the heat ends to be a liquid and, moreover, quantum physics was born. Einstein said, “He (Planck) has given one of the most powerful impulses to the progress of science.”
Without knowing infrared radiation, people have used “infrared thermometers” and “infrared heat” for technological purposes for thousands of years. For example, glass craftsmen, when the melted mass reaches the desired color and brightness, they know they can form it. The Egyptian bricks were dried in the sun. The thermometer was invented by Galileo (1605), 200 years before discovering infrared radiation. Nowadays infrared detectors are used in civil and military applications. For example, contactless thermometers, rocket detectors that strive for combat aircraft (detect infrared emissions of their turbines) or remote controls. Moreover, there are many animals that use infrared sensors to hunt their prey or to avoid their predators.
