Notes

Ultraviolet Rays …

Ultraviolet Rays is:
Sun is the important source of ultraviolet radiations, which is the main cause of suntans. Most of the ultraviolet light from sun is absorbed by atoms in the upper atmosphere i.e., stratosphere, which contains ozone gas. This ozone layer then radiates out the absorbed energy as heat radiation. Thus, the lethal (harmful to living beings) radiations get converted into useful heat radiations by the ozone gas, which warms the stratosphere. These ultraviolet rays are used in killing the bacteria in drinking water, in sterilisation of operation theatres and also in checking the forgery of documents.