Albert Einstein explained the photoelectric effect in 1905 by proposing that light consists of discrete packets of energy called photons, rather than being purely a wave. His explanation resolved why classical wave theory couldn’t account for the observed results. Here’s how he did it:
- Photon Concept:
- Einstein suggested that each photon carries energy proportional to its frequency: E=hfE = h f where EE is photon energy, hh is Planck’s constant, and ff is the frequency of light.
- Energy Transfer:
- When a photon strikes an electron on a material’s surface, it transfers its energy to the electron.
- If this energy is greater than the work function (ϕ\phi) of the material, the electron is ejected.
- Work Function and Kinetic Energy:
- The maximum kinetic energy of the ejected electron is: Kmax=hf−ϕ
- This explained why increasing light intensity alone doesn’t eject electrons if the frequency is below the threshold.
- Key Insight:
- Only the frequency of light determines whether electrons are emitted, not the intensity.
- This provided direct evidence for the particle nature of light, supporting quantum theory.
In short: Einstein explained that light behaves as particles (photons) whose energy depends on frequency, and that only photons with enough energy can eject electrons—revolutionizing our understanding of light and quantum physics.
I can also make a simple diagram showing photon impact and electron emission if you want a visual explanation—it helps a lot in understanding. Do you want me to do that?