Einstein and the Photoelectric Effect

In 1887, Heinrich Hertz discovered the photoelectric effect, an anomaly where light dislodges electrons from metal that classical wave theory failed to explain. Philipp Lenard later demonstrated that electron emission depended on light frequency rather than brightness. Building upon Max Planck’s concept of energy quanta, Albert Einstein proposed in 1905 that light travels as discrete energy packets defined by the equation E equals hf. Overcoming an electron's work function required single high-frequency packets rather than intense continuous waves. Following experimental confirmations by Robert Millikan and Arthur Compton, Einstein received the 1921 Nobel Prize, establishing the photon concept and foundational quantum physics. Sources https://en.wikipedia.org/wiki/Photoel... https://www.britannica.com/science/ph... https://unacademy.com/content/neet-ug... https://history.aip.org/exhibits/eins... https://www.europhysicsnews.org/artic... https://quarknet.org/sites/default/fi... http://mapageweb.umontreal.ca/leonell... https://www.nobelprize.org/prizes/phy... https://www.nobelprize.org/prizes/phy... https://timesofindia.indiatimes.com/e... https://physicstoday.aip.org/features... https://www.britannica.com/science/Co... http://labs.plantbio.cornell.edu/wayn... https://en.wikipedia.org/wiki/Gilbert... https://www.semanticscholar.org/paper...