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GR0177 #31
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Alternate Solutions |
FutureDrSteve
2011-11-07 12:22:35 | Oops, this was supposed to be a separate post, not a reply....
If you realize that the ground state energy of positronium is roughly -6.8eV (which I think you have to in order to solve this problem), you don't have to do any math. An electron transitioning down from n= would have initial potential energy of 0, and drop down to final energy -6.8eV, for a max energy change of 6.8eV, eliminating (C), (D), and (E). Since the electron is only falling down from n=3, it stands to reason that the photon would be less energetic than 6.8eV, leaving only answer (A). |  |
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Comments |
bill92
2014-10-27 13:17:41 | I just took the exam and there was no positronium question! All my studying was for naught!
Just kidding, I think it went well. Thanks to Yosun for this very helpful site! |  | FutureDrSteve
2011-11-07 12:22:35 | Oops, this was supposed to be a separate post, not a reply....
If you realize that the ground state energy of positronium is roughly -6.8eV (which I think you have to in order to solve this problem), you don't have to do any math. An electron transitioning down from n= would have initial potential energy of 0, and drop down to final energy -6.8eV, for a max energy change of 6.8eV, eliminating (C), (D), and (E). Since the electron is only falling down from n=3, it stands to reason that the photon would be less energetic than 6.8eV, leaving only answer (A). | | Tommy Koulax
2007-10-31 17:48:57 | Why is the reduced mass m/2 ?
nick1234
2007-11-02 17:16:11 |
For the hydrogen atom,  dominates the denominator, and  becomes 
For positronium,  , so 
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| | rinnie
2007-03-26 21:27:49 | Hydrogen levels E3 - E1 = -1.5 + 13.6 = 12.1/2 = 6.05.
Energy level of positronium is half those of Hydrogen.
FutureDrSteve
2011-11-07 12:20:53 |
If you realize that the ground state energy of positronium is roughly -6.8eV (which I think you have to in order to solve this problem), you don't have to do any math. An electron transitioning down from n= would have initial potential energy of 0, and drop down to final energy -6.8eV, for a max energy change of 6.8eV, eliminating (C), (D), and (E). Since the electron is only falling down from n=3, it stands to reason that the photon would be less energetic than 6.8eV, leaving only answer (A).
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You are replying to:
Oops, this was supposed to be a separate post, not a reply....
If you realize that the ground state energy of positronium is roughly -6.8eV (which I think you have to in order to solve this problem), you don't have to do any math. An electron transitioning down from n= would have initial potential energy of 0, and drop down to final energy -6.8eV, for a max energy change of 6.8eV, eliminating (C), (D), and (E). Since the electron is only falling down from n=3, it stands to reason that the photon would be less energetic than 6.8eV, leaving only answer (A). |
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