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Using the conservation laws, demonstrate that a free electron cannot absorb a photon completely. |
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Answer» Solution :We consider the collision in the rest frame of the initial ELECTRON. Then the reaction is `gamma+e (rest)rarr e("MOVING")` Energy momentum conservation GIVES `cancelh omega +m_(0)c^(2) = m_(0)c^(2)//SQRT(1-beta^(2))` `(cancelh omega)/(c ) = (m_(0)cbeta)/(sqrt(1-beta^(2)))` where `omega` is the ANGULAR frequency of the photon. Eliminating `h omega` we get `m_(0)c^(2) = m_(0)c^(2)(1-beta)/(sqrt(1-beta^(2))) =m_(0)c^(2) sqrt((1-beta)/(1+beta))` This gives `beta = 0` which implies `cancelh omega = 0`. But a zero photon means a photon. |
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