Discussion Forum



1)

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 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) $\frac{A}{(A+1)^{2}}E$

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

D) $\frac{(A-1)}{(A+1)^{2}}E$

Answer:

Option C

Explanation:

Fraction retained by the nucleus 

 1102021662_j8.PNG

 

$\left(\frac{\triangle k}{k}\right)_{retained}=\left(\frac{m_{2}-m_{1}}{m_{1}+m_{2}}\right)^{2}=\left(\frac{A-1}{A+1}\right)^{2}$

After collision kinetic energy retained by neutron 

$\left(\frac{A-1}{A+1}\right)^{2}E$