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Quick physics question

  • 07-06-2011 7:24pm
    #1
    magicianz
    Registered Users, Registered Users 2 Posts: 1,115 ✭✭✭


    Just wondering to what extent do we need to know Einstein's Photoelectric Law?
    What points do we have to know?

    What I know already is:
    The velocities of the electrons emitted by the photoelectric effect range from zero to a definite maximum value.
    The maximum velocity (and therefore the maximum kinetic energy) of the emitted electrons depends on the frequency of the light but not the intensity.

    Whats the part of it that does depend on the intensity? Number of electrons emitted?


Comments

  • #2
    electrictrad
    Registered Users, Registered Users 2 Posts: 367 ✭✭electrictrad


    magicianz wrote: »
    Just wondering to what extent do we need to know Einstein's Photoelectric Law?
    What points do we have to know?

    What I know already is:
    The velocities of the electrons emitted by the photoelectric effect range from zero to a definite maximum value.
    The maximum velocity (and therefore the maximum kinetic energy) of the emitted electrons depends on the frequency of the light but not the intensity.

    Whats the part of it that does depend on the intensity? Number of electrons emitted?

    For Einsteins Photoelectric Law, we need the following, for a big marker(12+);

    1. Light is a stream of quantums/photons of energy

    2. Energy given by E=hf

    3. Brighter a light source(intensity of light) => more photons per second

    4. Energy required to release loosest electron = work function of that metal

    5. All energy of 1 photon given to one electron

    6. Energy greater than Work Function => electron is released

    7. Energy less than Work function => electron not released

    8. Excess energy is given to the electron as kinetic energy, ie hf = work function + (1/2)mv2


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