03 Feb What are Ultraviolet Rays?
Have you ever looked at the sunbeam coming through the windows while you are taking your physics tuition? If not, you definitely felt them over your shoulder while taking a walk down the street on a sunny morning? Have you given a thought to the composition of the sunlight? When the sunlight is allowed to pass through a prism, it splits into seven colours. These colours are violet, indigo, blue, green, yellow, orange and red. Wavelength wise distribution of these seven colours is known as a spectrum. Light travels in the form of waves. These waves are produced due to electrical oscillations.
In the seven colours of the sun’s spectrum, the wavelength of the violet colour is minimum while that of red is maximum. The observed wavelengths in the visible spectrum range from about 7.5 x 10-5 cm to 4 x 10 -5 cm. Radiations having a wavelength less than violet colour (4x 10-5) are known as Ultraviolet (UV) Rays. The energy associated with UV rays is quite high. Overexposure to UV rays can cause skin burns and may even lead to skin cancer. The sun produces a large amount of UV rays. But, most of it is absorbed by a layer of gas called ozone in the upper atmosphere of the earth, due to which very small amount reaches the earth. If the entire amount of UV rays were to reach us, life would not have been possible on earth.
Ultraviolet rays are also quite useful, but to a smaller extent. They kill certain bacteria and help change certain chemicals in the skin into vitamin D. But, these rays are extremely harmful to eyes. While working with ultraviolet light one must wear coloured glasses. So, next time you are playing or roaming under scorching sun, remember your physics tuition lessons and be prepared to wear a brimmed hat and a sunglass.