Quantum physics- kinetic energy of electron after collision

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Homework Help Overview

The discussion revolves around a quantum physics problem involving the kinetic energy of an electron after it collides elastically with an atom in its ground state. The original poster notes that the bombarding electron has a kinetic energy of 7.0 eV, which is insufficient to excite the atom, as it requires 10.4 eV for excitation. There is confusion regarding the expected outcome of the collision and the energy of the electron post-collision.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the energy requirements for excitation and ionization of the atom, questioning the transitions that can occur with the given energy. There are attempts to calculate the kinetic energy of the electron after potential transitions, with some participants seeking clarification on the original question and the implications of their calculations.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the energy transitions and their effects on the kinetic energy of the electron. Some calculations have been presented, but there is no consensus on the implications of these results, and further clarification is sought regarding the original question.

Contextual Notes

Participants note that the energy levels for excitation and ionization are critical to understanding the problem, and there is an emphasis on the need for clarity regarding the question being addressed. The original poster's initial assumptions about energy conservation in the collision are also under scrutiny.

desmond iking
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Homework Statement



since the bombarding electron has only 7.0eV ... it's not sufficient for the electron in the ground state to be excited which needs 10.4eV , so no excitation occur. and in my opinion, the bombarding electron should emerge with the same amount of energy ... but the ans given is here different . Can somoene explain what's the ans is about? thanks! [/B]

Homework Equations

The Attempt at a Solution


SAMPLE ANS : 7.0- ( (-3.7eV) - (-10.4eV) ) = 0.3eV...
 

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The picture does not show what the question is.
You cannot discuss the answer unless you know the question.:)
 
Sorry.. The question should be
If the kinetic energy of an electron 7.0eV collides elastically with an atom in ground state , what's the kinetic energy of the elctron after collision? Ps I forgot to post the question...
 
It need 10.4 eV to ionize the atom but not to excite it.
The atom can go from the ground state to one of the other states in the diagram. This transition will require less than 10.4 eV. Which transitions are possible in this case?
 
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nasu said:
It need 10.4 eV to ionize the atom but not to excite it.
The atom can go from the ground state to one of the other states in the diagram. This transition will require less than 10.4 eV. Which transitions are possible in this case?
-10.4eV to- 5.5eV , -10.4eV to -3.7eV are possible
 
What will be the KE of the initial electron after each of these two processes?
 
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for -10.4eV to- 5.5eV , using ke= hf-W
i have ke= 7.0eV - ( 10.4-5.5) = 2.1eV
for -10.4eV to -3.7eV , i have ke= 7.0eV - ( 10.4-3.7) =0.3eV

so? what does it mean?
 
What do you mean?
What was the question, again?
 
nasu said:
What do you mean?
What was the question, again?
If the kinetic energy of an electron 7.0eV collides elastically with an atom in ground state , what's the kinetic energy of the elctron after collision?
 
  • #10
So what did you find in the previous calculation? Were not these values of kinetic energy after collision?
 

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