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Photoelectric Effect

The Photoelectric Effect demonstrates that light can behave as particles (photons) and can eject electrons from a metal surface when the light has sufficient energy. This phenomenon played a key role in the development of quantum mechanics.

Key Principles​

  • Photon Energy: Each photon has energy E = hν, where h is Planck’s constant and ν is the frequency of light.
  • Work Function (φ): Minimum energy required to remove an electron from a metal.
  • Kinetic Energy of Ejected Electrons:
    KE = hν − φ

Observations​

  1. Electrons are emitted only if the light’s frequency exceeds a threshold frequency (ν₀).
  2. Increasing light intensity increases the number of electrons emitted, not their kinetic energy.
  3. Increasing light frequency above the threshold increases the kinetic energy of electrons.

Importance​

  • Demonstrates quantization of energy in light.
  • Supports the particle nature of light, complementing the wave theory.
  • Forms the foundation for technologies like photocells, solar panels, and photo detectors.

Applications​

  • Photovoltaic cells for generating electricity from sunlight.
  • Photoelectron spectroscopy for analyzing electronic structure of materials.
  • Light sensors in cameras and scientific instruments.

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