In 1928,who discovered that when a ray of coloured light enters a liquid, a fraction of the light scattered by that liquid is of a different colour?

CV Raman

The correct answer is option 2. CV Raman.

In 1928, Indian physicist Sir C.V. Raman discovered the phenomenon of light scattering, which came to be known as the Raman effect. When a beam of light passes through a transparent material, a small fraction of the light is scattered in different directions. What was remarkable about Raman's discovery was that he observed that a small portion of this scattered light had different wavelengths than that of the incident light. This phenomenon occurs due to the interaction of light with the vibrational and rotational modes of molecules in the material.

The Raman effect provided significant insights into the molecular structure of substances. It allowed scientists to study the vibrational and rotational energy levels of molecules, leading to advancements in fields such as chemistry, physics, and materials science. Raman spectroscopy, based on this effect, has become a powerful tool for analyzing the composition, structure, and properties of various materials, including gases, liquids, and solids.