Waves and radiations. Gershel

you are: Waves and radiations

Well and what it is possible to tell about other end of a spectrum? Whether this part of a spectrum possesses any properties which would allow to find out it? The answer to this question was received in 1800 by English astronomer John Gershel (1792-1871). He was interested in heating ability of beams of various colours of a spectrum and directed them on zachernennyj a ball of the sensitive thermometer. Gershel has established that the thermal effect amplifies in a direction by the red end of a spectrum, and continues to amplify and behind its limits: it already operates an infra-red part of a spectrum.

In 1840 Gershel has thought up a way ' photographing ' a sunlight spectrum on its heating ability. It has covered a strip of a paper with glue and a lamp soot that it well absorbed heat, has dipped it into spirit and has directed on it the sunlight spread out in a spectrum. There, where the strip received more than heat, spirit evaporated faster, and it was possible to observe a spectrum in the form of a strip with variable humidity. Gershel has found out such way new fraungoferovy lines in infra-red area of a spectrum.

Knowing that the solar spectrum falls outside the limits both ends of area of visible light, it is easy to imagine that it can be stretched and further. There are no bases to expect that it is possible to find out limits in general. But as we saw that all three properties - visual effect, thermal effect and chemical activity - concern only certain parts of a spectrum, we do not know, what else properties could be used for the further searches. As often happens in the physicist, the answer has come absolutely on the other hand.