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What is the photoelectric effect?

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Quick answer

The photoelectric effect is when light hitting a material knocks electrons loose from it. Einstein explained it by proposing that light comes in packets (photons) — work that helped launch quantum physics and underpins solar panels and digital cameras. Light striking a material can eject electrons.

Key things to understand

  1. Light striking a material can eject electrons.
  2. Einstein explained it using light 'packets' (photons).
  3. It helped found quantum physics.
  4. It powers solar cells and light sensors.

People also ask

What is the photoelectric effect?
The release of electrons from a material when light shines on it.
Why is the photoelectric effect important?
Einstein's explanation showed light behaves as particles (photons), a foundation of quantum physics.
Where is the photoelectric effect used?
In solar panels, light meters, image sensors, and many light-detecting devices.