Science

Water colours

A glass of water has no colour. But a deep sea with the same water is a brilliant blue. Why is this so?

This was the question that C.V. Raman asked himself in 1921 on seeing the colour of the Mediterranean sea from a ship. He immediately began to conduct experiments on board the ship using some simple instruments he had with him. At that time, scientists believed the sea was blue because it reflected the colour of the sky, but Raman found that it was the water itself that caused blue light to scatter more than other colours in light.

At that time Raman was a professor at the University of Calcutta. He returned from his visit of England and Europe and started experiments to study how light behaved when it passed through various substances. On February 28, 1928, one of the experiments gave a clear result. Light of only one colour was passed through a liquid, but the light that emerged had small traces of another colour. This meant that the molecules in the liquid were changing the colour of some of the light passing through it. The discovery created a sensation around the world and was named the Raman Effect. In 1930, C.V. Raman became the first person from Asia to be awarded a Nobel prize in any field of science. The date of the discovery, February 28, is now celebrated as National Science Day in India.

The Raman effect has been very useful in many areas of science. It was found that when light was passed through a substance, a series of colours were seen that could be thought of as a fingerprint of the substance. This idea has been used in chemistry, medicine, biology and many other areas of science to find out what a substance is made of. Recently, people have used the idea to make a device called a Raman Scanner. It can be pointed at a substance to tell what it is. Police have begun to use this scanner to find out if people are carrying any banned substances.

Not all of us will be as brilliant as C.V. Raman. But on the occasion of National Science Day we must remember that we can all be just as curious about the world as he was.

Simply brilliant

Raman was a man of extraordinary ability. He passed his Std. X when he was just 11 years old. At 15 he had a degree, with gold medals in Physics and English. By the time he was 19 he had an MA. Professors at college used to allow him to skip science classes because they knew he didn't need them. In addition to being brilliant, Raman was also intensely curious about the world around him. We saw how his curiosity about the colour of the sea led to the discovery of the Raman Effect. Similarly, his curiosity led to a wide range of scientific work. On his 1921 trip to England he was taken to see St. Paul's Cathedral. Raman became so excited by the whispering gallery there that he performed some experiments and wrote scientific papers about it. As a child, Raman had seen his father play the violin. Much of his life's research work was about the science behind music. He also investigated the effect of sound on light and the structure of crystals. His collection of crystals is preserved at the Raman Research Institute in Bangalore.

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Printable version | Apr 13, 2021 8:07:06 AM | https://www.thehindu.com/sci-tech/science/water-colours/article2937811.ece

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