The photoelectric effect

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  • Created by: Lucy
  • Created on: 13-11-12 18:44
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  • The Photoelectric effect
    • If you shine light of a high enough frequency onto the surface of a metal, it will emit electrons.
      • 1) Free electrons on the surface of the metal absorb energy from the light, making them vibrate.
      • 2) If an electron absorbs enough energy, the bonds holding it to the metal break and the electron is released.
      • 3) This is called the photoelectric effect and the electrons emitted are called phoyoelectrons.
    • Before an electron can leave the surface of a metal,it needs enough energy to break the bonds holding it there, this energy is called the work function energy (symbol ?, (phi))
      • For electrons to be released,     hf > ?
        • Therefore f= ?/h
      • Maximum kinetic energy is given by: hf=? +  ½mvmax²
        • The kinetic energy it will be carrying when it leaves the metal if hf minus any energy it's lost on the way out
        • The kinetic energy of the the electrons is independent of the intensity, because they can only absorb one photon at a time.
    • The maximum kinetic energy increases with the frequency of radiation, but is unaffected by the intensity of the radiation.
    • The number of photoelectrons emitted per second is proportional to the intensity of the of the radiation.

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