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Homework Help: Where does an electron emit or absorb radiation

  1. Oct 12, 2012 #1
    1. The problem statement, all variables and given/known data
    Where does a electron emit or absorb radiation?

    2. Relevant equations
    L=mvr=nh (h is diracs constant)
    hf = En1 - En2

    3. The attempt at a solution
    I know that in a stationary state an electron cannot emit EM waves, but that if it shifts down the difference between the two goes into energy for EM waves. So does this happen for upward shifts, like if you were at n=1 and went to the first excitation level n=2 for hydrogen would that work as well? Also what excactly is a stationary state is it the level like n=2,3,4 and so on, which is what I assume. Furthermore at the ground state n=1 is any light emitted I would think not because n1=n2 and (lamda) = (lamda)'(n1^2/n1^2-n2^2) you would get a division by zero and the equation would fail which would not permit any light. (Also (lamda)' is the wavelength limit in the equation given).
  2. jcsd
  3. Oct 12, 2012 #2
    An actually I guess I stated the energy diff going into hf wrong I guess it doesnt actually for EM waves I meant EM radiation becuase hf is the enrgy of the photon that is formed.
  4. Oct 12, 2012 #3
    I think I understnad that a stationary state is a special state of motion so when it is viewed it always seens at the same L value I think because L is quantized in the abiove equation and (diracs constant) is locked to an integer value which cant be in bewteen so that would tell me that from everthing I have said energy can only be emitted or absorbed when a shift occurs none can occur at ground I am assuming and none at the stationary states. But I really do need help, I am sorry im I ramble and it is confusing.
  5. Oct 13, 2012 #4
    Yes, it is confusing. What exactly is the problem you are trying to solve?
  6. Oct 13, 2012 #5
    I am trying to figure out what a stationary level actually is I guess and also is ground stage the same as staionary since no EM radiation occurs there
  7. Oct 13, 2012 #6
    More of a conceptual question I guess
  8. Oct 13, 2012 #7
    There is only one stationary state of an atom, also known as the ground state. It is the lowest possible energy state of an atom. Any other state is unstable, an atom must be "excited" to enter such a state, and it will eventually go back to the ground state (unless there is an influx of energy); an atom emits energy when going from a higher energy state to a lower energy state, and absorbs energy otherwise.
  9. Oct 13, 2012 #8
    Sweet thanks man you answered my question.
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