MCQ
A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is
- A$16/81$
- ✓$8/9$
- C$8/27$
- D$2/3$
✓
Answer
Correct option: B.
$8/9$
b
(b)Fractional decrease in kinetic energy of neutron
=$1 - {\left( {\frac{{{m_1} - {m_2}}}{{{m_1} + {m_2}}}} \right)^2}$[As $m_1=1$ and $m_2 = 2$]
$ = 1 - {\left( {\frac{{1 - 2}}{{1 + 2}}} \right)^2}$$ = 1 - {\left( {\frac{1}{3}} \right)^2} = 1 - \frac{1}{9} = \frac{8}{9}$
(b)Fractional decrease in kinetic energy of neutron
=$1 - {\left( {\frac{{{m_1} - {m_2}}}{{{m_1} + {m_2}}}} \right)^2}$[As $m_1=1$ and $m_2 = 2$]
$ = 1 - {\left( {\frac{{1 - 2}}{{1 + 2}}} \right)^2}$$ = 1 - {\left( {\frac{1}{3}} \right)^2} = 1 - \frac{1}{9} = \frac{8}{9}$
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