Question

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

Answer 1

Infrared radiations are the electromagnetic waves of wavelength in the range of 8000Å 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 the 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 purposes by doctors.