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1 a.m.u is defined as 1/12th of the mass of an atom of 6C12 isotope.
It can be shown that1 a.m.u = 1.66 x 1027 kg.
According to Einstein, mass energy equivalenceE = mc2
Where m = 1.66 x 10-27 kg.C = 3x108 m/sec ,we get
E = 1.49 x 10-10 J (1Mev = 1.6 x 10-13 J)
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.Isotopes
Isotopes of an element have same atomic number (Z) but different mass numbers (A).
For example, 1H1, 1H2, 1H3 are isotopes of hydrogen;Nuclear Forces
In spite of the strong electrostatic force of repulsion between protons, nucleus of most elements are stable. This is because of the strong forces of attraction, which hold together the nucleons in that tiny volume.
These forces are short-range forces and are the strongest in nature. They are operative up to distances of the order of a few fermi. They are charge-independent, non-central and non-conservative forces.
