- August 18, 2021
- Posted by: OptimizeIAS Team
- Category: DPN Topics
Subject – Science and Tech
Context – Einstein received the 1921 Noble Prize in 1922, for “his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect”.
- ‘Annus Mirabilis’, or the Year of Miracles, is how 1905 is remembered by physicists because Einstein, only 26 then, published four remarkable papers that year.
- One of them explained that light was made of photons and when light shone on metal, each photon’s energy correlated to electron’s speed on the metal’s surface. This redefined the composition of light and Einstein himself dubbed it revolutionary. It was for this that he received the Nobel Prize.
- Light, Einstein said, is a beam of particles whose energies are related to their frequencies according to Planck’s formula. When that beam is directed at a metal, the photons collide with the atoms. If a photon’s frequency is sufficient to knock off an electron, the collision produces the photoelectric effect.