question_answer

A neutron is moving with velocity u. It collides head on and elastically with an atom of mass number A. If the initial kinetic energy of the neutron is E , then how much kinetic energy will be retained by the neutron after reflection?

A) \[{{\left( \frac{A}{A+1} \right)}^{2}}E\]                 

B)  \[\frac{A}{{{\left( A+1 \right)}^{2}}}E\]

C)  \[{{\left( \frac{A-1}{A+1} \right)}^{2}}E\]                            

D) \[\frac{\left( A-1 \right)}{{{\left( A+1 \right)}^{2}}}E\]

Correct Answer: C

Solution :

 The fraction of total retained by nucleus \[=2.35\times {{10}^{-2}}m\] Kinetic energy retained by neutron after collision is \[r=2.35m\]