Binding Energy Explained
The nucleons are held together by nuclear force, which is short ranged but much stronger than coulomb force. It is found that the mass of a nucleus is less than the sum of the mass of the individual nucleons. What does this mass defect signify?
The mass-defect is responsible for the binding together of the nucleons.
Let us understand how this mass defect arises.
When individual nucleons come together to form a nucleus, they liberate some energy in the form of photons. The liberated energy appears as a reduction in the net mass of the nucleus following Einstein's mass energy relation()
The same energy needs to be supplied back to the nucleus if we need to separate the nucleus into its individual nucleons. To overcome the nuclear forces holding the nucleus together, energy equivalent to the binding energy needs to be supplied.
To take as an example, let us find out the binding energy of a Helium nucleus