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National Science Day

Topics Covered: Science and Technology- developments and their applications and effects in everyday life Achievements of Indians in science & technology; indigenization of technology and developing new technology.

National Science Day

What to study?
For Prelims: Raman Effect, NSD and other achievements of CV Raman.
For Mains: Significance of the day.

Context: 28th February is celebrated as National Science Day (NSD) in India. NSD is celebrated to commemorate discovery of the ‘Raman Effect’, which led to Sir C.V. Raman winning the Noble Prize.

The first National Science Day was celebrated on February 28, 1987.

 

Theme:

This year, the theme for National Science Day 2020 is “Women in Science”, which aims to appreciate the contribution of women in the field of science.

 

What is Raman Effect?

A phenomenon in spectroscopy discovered by the eminent physicist Sir Chandrasekhara Venkata Raman in 1928.

Raman Effect is a change in the wavelength of light that occurs when a light beam is deflected by molecules.

  • When a beam of light traverses a dust-free, transparent sample of a chemical compound, a small fraction of the light emerges in directions other than that of the incident (incoming) beam.
  • Most of this scattered light is of unchanged wavelength. A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman Effect.

 

Raman’s experiment:

The violet light of the solar spectrum is isolated with a violet filter and passed through the liquid sample. Most of the light emerging from the liquid sample is the same color as the incident violet beam: the so-called Rayleigh scattered light (the scattering of light by particles in a medium, without change in wavelength. It accounts, for example, for the blue colour of the sky, since blue light is scattered slightly more efficiently than red).

 

However, Raman, along with K S Krishnan was able to show that some of the scattered light was a different color, which they could isolate by using a green filter placed between the observer and the sample.

Scattering_liquid

Sources: pib.