What is the photoelectric effect?
Quick Answer
The photoelectric effect is the emission of electrons from a material when it absorbs light of sufficiently high frequency. It helped establish the quantum nature of light.
The Full Story
The photoelectric effect occurs when photons transfer energy to electrons in a material, allowing the electrons to escape. Classical wave theory could not explain why light below a certain frequency failed to eject electrons, even if it was bright. Albert Einstein explained the effect in 1905 by proposing that light comes in discrete packets of energy, called photons, a breakthrough that helped launch quantum physics. The Nobel Prize in Physics was awarded to Einstein in 1921 partly for this work.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The experiment that proved light comes in packets"