- #1
simon96c
- 11
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Hello everyone, I have a question regarding a formula which can be derived from conservation of momentum and energy in the Compton effect.
From conservation of momentum and energy during the collision of a photon with an electron, it is possible to get two expressions for the final energy E of the electron:
E^2=(Q_0-Q)^2+2(Q_0-Q)m_0*c^2+(m_0*c^2)^2
and
(cP)^2=Q_0^2-2*QQ_0cosΘ+Q^2
where Q and Q_0 are the final and initial energies of the photon and Θ the angle between the momentum vector of the photon before hitting the electron and after.
The problem arises when, to derivate the final formula, the two equations are subtracted and one term seems to go missing, as the book says it is:
2QQ_0(1-cosΘ)-2(Q_0-Q)m_0c^2=0
whereas I have
2QQ_0(1-cosΘ)-(2Q_0-2Q-m_0c^2)m_0c^2=0, so I basically have a "m_0c^2" which should not be there.
Could some explain what I'm missing there?
I'm sure it's something really silly, so thanks in advance for the answers! :)
From conservation of momentum and energy during the collision of a photon with an electron, it is possible to get two expressions for the final energy E of the electron:
E^2=(Q_0-Q)^2+2(Q_0-Q)m_0*c^2+(m_0*c^2)^2
and
(cP)^2=Q_0^2-2*QQ_0cosΘ+Q^2
where Q and Q_0 are the final and initial energies of the photon and Θ the angle between the momentum vector of the photon before hitting the electron and after.
The problem arises when, to derivate the final formula, the two equations are subtracted and one term seems to go missing, as the book says it is:
2QQ_0(1-cosΘ)-2(Q_0-Q)m_0c^2=0
whereas I have
2QQ_0(1-cosΘ)-(2Q_0-2Q-m_0c^2)m_0c^2=0, so I basically have a "m_0c^2" which should not be there.
Could some explain what I'm missing there?
I'm sure it's something really silly, so thanks in advance for the answers! :)