The Photoelectric Effect: Light Knocking Out Electrons

The photoelectric effect happens when light hits a material and ejects electrons from it.
Einstein explained it in 1905 by showing that light comes in particles called photons.
Each photon carries energy based on its frequency, not its brightness.
If the photon’s energy is too low, no electrons are released, no matter how intense the light.
Higher-frequency light, like ultraviolet, can knock out electrons even at low intensity.
The effect proved that light behaves as both waves and particles.
This discovery won Einstein the 1921 Nobel Prize in Physics.
Photocells, used in solar panels and sensors, rely on the photoelectric effect.
Streetlights that switch on at dusk use photoelectric sensors to detect light levels.
The photoelectric effect laid the foundation for quantum mechanics and modern electronics.