Question

One atomic mass units is equivalent to .............. MeV energy.

Answer 1

1 a.m.u is defined as $1/{12}^{th}$ of the mass of an atom of $6^{C^{12}}$ isotope.

It can be shown that

1 a.m.u $=1.66\times {10}^{27}kg.$

According to Einstein, mass energy equivalence

$E=m{c}^2$

Where $m=1.66\times {10}^{-27}kg$

$C=3\times {10}^{8}m/sec,$ we get

$E=1.49\times {10}^{-10}J(1Mev=1.6\times {10}^{-13}J)$

$E=\frac{1.49\times {10}^{-10}J}{1.6\times {10}^{-13}}Mev$

$E=931.25Mev$

Hence a change in mass of 1a. m.u (called mass defect) releases an energy equal to 931 Mev.

1 amu $=931$ Mev is used as a standard conversion.