"A small fraction of the light comes out in directions different from that of the incoming beam." "Fraction"…

Every year on 28 February, India celebrates National Science Day. The date marks the discovery of the Raman Effect in 1928 by the physicist Sir C. V. Raman, while he was working in the laboratory of the Indian Association for the Cultivation of Science in Kolkata. For this discovery he was awarded the Nobel Prize in Physics in 1930.

The Raman Effect is about what happens to light as it passes through a substance. When a beam of light goes through a clear, dust-free sample of a chemical compound, a small fraction of the light comes out in directions different from that of the incoming beam: it is scattered. Most of this scattered light keeps its original wavelength. But a small part of it comes out with a different wavelength, caused by the molecules that the light meets, and the presence of this changed light is the Raman Effect. The discovery belongs to spectroscopy, the branch of science that studies substances by means of light.

The idea of a National Science Day came from the National Council for Science and Technology Communication, which in 1986 asked the Government of India to name 28 February for it. The government agreed, and the first National Science Day was held on 28 February 1987. Its aim is to spread the message of how important science is in people's daily lives, and every year it has its own theme.