Question

What are infrared radiations ? How are they detected ? State one use of these radiations.

Answer 1

Infrared radiations are the electromagnetic waves of wavelength in the range of $8000$ Å to ${10}^7$ Å .
$Detection$ : If a thermometer with a blackened bulb is moved from the violet end towards the red end, it is observed that there is a slow rise in temperature , but when it is moved beyond the red region, a rapid rise in temperature is noticed. It means that the portion of spectrum beyond the red end has certain radiations which produce a strong heating effect , but they are not visible. These radiations are called the infrared radiations.
$Use$ : The infrared radiations are used for therapeutic purpose by doctors and in satellite communication ..