Q.(a) Draw a plot showing the variation of potential energy of a pair of nucleons as a function of their separation. Mark the regions where the nuclear force is

The strong (nuclear) force is the fundamental interaction responsible for holding the nucleus together, acting between nucleons (proton-proton, proton-neutron, and neutron-neutron alike) and overcoming the electrostatic repulsion that would otherwise push the positively charged protons apart. Though not yet completely understood theoretically, its key experimentally established properties are well established.

It is by far the strongest of the fundamental forces at nucleon-scale separations, roughly 100 times stronger than the electrostatic force between the same particles at the same distance -- strong enough to comfortably overcome proton-proton electrostatic repulsion within a typical nucleus. It has an extremely SHORT range, strong over distances of only a few fm but falling essentially to zero for any larger separation, in sharp contrast to gravity and electromagnetism, whose influence in principle extends to infinite distance. And it is CHARGE-INDEPENDENT: the force between two neutrons, two protons, or a proton and a neutron, all at the same separation, is experimentally the same strength -- the nuclear force does not distinguish nucleons by their electric …