Q122 · Practice questionSimple familiar1 mark
QUESTION 122
An electron and positron annihilate from rest. Momentum conservation requires the final state to include at least
(A)
one proton
(B)
one photon
(C)
two photons
(D)
one neutrino only
WORKED SOLUTION
1 markAnswer C
ANSWER
C. two photons
Worked solution
Two photons can carry equal and opposite momenta; a single photon cannot have zero total momentum while carrying the released energy.
Selects the correct option.
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