Comparison of the binding energies of \( {}^2\mbox{H} \) (deuteron), \( {}^3\mbox{H} \) (triton), \( {}^4\mbox{He} \) (alpha - particle) show that the nuclear force is of finite range (\( 1-2 \) fm) and very strong within that range.

For nuclei with \( A>4 \), the energy saturates: Volume and binding energies of nuclei are proportional to the mass number \( A \) (as we saw from exercise 1).

Nuclei are also bound. The average distance between nucleons in nuclei is about \( 2 \) fm which must roughly correspond to the range of the attractive part.