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Thread: Planck's constant h is defined: unity of action.A photon has energy= h*f. What has

  1. #1 Planck's constant h is defined: unity of action.A photon has energy= h*f. What has 
    Join Date
    Jul 2011
    energy of a photon to be called action energy?, what is it currently called just Energy?,
    for the time being, I'll call it Ea

    the dimension of h, of Ea is Joule*sec => N*m*srg
    the dimension of Ek is Joule

    can you explain what happens to dimensions in Compton scattering, or when an electron drops on a lower orbit?
    when Ea turns into Ek and vice versa?
    why dimensions should change?

    and could you explain dimensions in E = mC^ 2, I suppose E means Ea. One electron is transfromed in Me = 1.2356x 10^ 20 h

    Last edited by phyz; July 24th, 2011 at 09:02 AM.
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  3. #2  
    Forum Bachelors Degree x(x-y)'s Avatar
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    Jul 2010

    is the formula for Photon energy (the quantised amount of energy that 1 photon of electromagnetic radiation of a certain frequency has) not action energy. And by dimensions I think you mean units, do you not?

    The units for E in E = hf are Joules (although, they are commonly expressed in eV- electronvolts- due to the very low amount of energy involved), which comes from (in terms of units):

    Hz is just s-1 and so:

    which obviously makes sense!

    When an electron drops to a lower energy state in an atom, it emits a photon of electromagnetic radiation with energy corresponding to the energy difference between the two energy states it dropped between.

    "Nature doesn't care what we call it, she just does it anyway" - R. Feynman
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