photons

• Photoelectric effect


  The emission of electrons from a metal surface when light shines on it
• Einstein's explanation for the photoelectric effect

  • Photons carry energy and momentum
  • Photon energy depends on frequency
  • Photon energy is absorbed by a single electron

  
• Work function


  The minimum energy required to remove an electron from a material
• Cut-off frequency


  The minimum frequency of light required to eject photoelectrons from a material

  
• Electron-volt (eV)


  The energy required to move an electron through a potential difference of 1 volt
• Photon momentum


  Photons have momentum given by p = h/λ

  
• Compton scattering


  • Photon-electron interaction
  • Photon wavelength shifts depend on scattering angle
  • Relativistic effects must be considered

  
• Plum pudding model


  Early model of the atom with electrons randomly arranged in a positively charged sphere
• Rutherford scattering


  • Alpha particles scattered by a dense, positively charged nucleus
  • Allowed estimation of nucleus size