Step 1: On 28 February 1928, the Indian physicist C. V. Raman discovered that when light passes through a transparent material, a small part of it is scattered with a change in wavelength. Step 2: This phenomenon is called the Raman effect (Raman scattering). Step 3: Raman received the Nobel Prize in Physics in 1930 for this work; he was the first Asian scientist to win a Nobel Prize in science. Step 4: India has celebrated 28 February as National Science Day since 1987. Answer: Raman effect.