em spectrum, de broglie, pe notes

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  • de Broglie Wavelength

  • de Broglie Pictured the electron in its circular orbit as a

    particle wave Can produce "standing waves" under

    resonant conditions Developed the idea that a particle with mass,

    m, and a velocity, v, has a wavelength associated with it => de Broglie Wavelength

  • de Broglie

  • de Broglie

  • de Broglie

  • Schrdinger Used de Broglie wavelength to

    create a quantum theory based on waves

    Did not keep the "orbits" The wave/particle model cannot

    determine the location and momentum of an electron at the same time

    The quantum model predicts the probability that an e- is at a specific location

  • Heisenberg Uncertainty Principle Can only determine the

    location or the momentum (velocity) of the particle - not both at the same time!

  • Photons and Photoelectric Effect

  • Photoelectric Effect

    Metal is illuminated by electromagnetic radiation

    Energy that is absorbed near the surface can free electrons, causing e's to fly off

    Released electrons are called photoelectrons

  • Significant time delay between the illumination and ejection - build up of KE to free e-'s

    Increasing the intensity of light = cause electrons to leave with greater KE

    Photoelectrons would be released regardless of frequency of light, as long as the intensity was great enough....

    But these are FALSE!

    Wave theory predicts the following:

  • Photoelectric EffectFindings

    Photons were ejected immediately Increasing the intensity did not change the KE

    although more e-'s were ejected, KE does not increase. If the frequency fell below a threshold (specific for

    each metal), no photoelectrons would be ejected, regardless of intensity!

    If the frequency increases above the threshold, KE increases linearly

  • PE Effect - Math

    Threshold Frequency Work Function - the minimum

    amount of energy required on a metal surface to eject an electron

    How are these two related?

  • PE Effect - Math

  • Photoelectric Effect

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