Nuclear Force

Forces that keep the nucleons bound in the nucleus are called nuclear forces (Fig. 2).

Fig. 2
• Nuclear forces are short range forces. These do not exist at large distances greater than 10â€“15 m.
• Nuclear forces are the strongest forces in nature.
• These are attractive forces and cause stability of the nucleus.
• These forces are charge independent.
• Nuclear forces are non-central force.
Nuclear forces are exchange forces According to scientist Yukawa the nuclear force between the two nucleons is the result of the exchange of particles called mesons between the nucleons.

Ï€ mesons are of three types: positive Ï€ meson (Ï€+), negative Ï€ meson (Ï€ â€“), and neutral Ï€ meson (Ï€0)

The force between neutron and proton is due to exchange of charged meson between them, i.e.,

The forces between a pair of neutrons or a pair of protons are the result of the exchange of neutral meson (Ï€0) between them i.e.,
and

Thus, exchange of Ï€ meson between nucleons keeps the nucleons bound together. It is responsible for the nuclear forces.