what are the merits and DE merits of ultra violet and infra red rays?

Answer 1

Infrared light is of lower energy than visible light. Usually it is associated with changes in the energy states of vibrating molecules, which in turn is related to temperature. Using devices that can detect IR light, we are able to see hotter objects (such as living beings) in contast to cooler objects (at normal room temperature) even without any visible light. It makes it useful for police to track dangerous suspects by removing all visible light, making the police invisible to the suspect, but visible to the police. In terms of interacting with living tissue, IR light is fairly harmless.

Ultraviolet light is of higher energy than visible light. It tends to cause a number of organic molecules to dissociate by breaking bonds which absorbs UV light. This causes so good things, such as stimulating the human body to produce vitamin D on its own. However, some reactions might be of DNA molecules in skin cells, which may produce cancerous cells. Melanoma (skin cancer) is perhaps the most common form of cancer.

This doesn't mean that UV light is bad in of itself. It is often used in the laboratory to explore and produce varying organic compounds, some of which may lead to pharmaceutical treatments. Also, it's good for detecting certain compounds. For example, we have a UV light detector that allows us to look for certain stains that our cats might leave behind. :-)