The → potential energy from which derives the repulsive
electrostatic force between two → charged particles.
For example, the Coulomb energy
between two protons is
e2/r ~ 0.5 MeV, which is small compared with the average
→ binding energy per particle (~ 8 Mev). However
the Coulomb repulsion becomes important for heavy nuclei. The total Coulomb energy
of a nucleus is given by: (3/5) Z(Z - 1)e2/R, where Z
is the → atomic number, e the charge, and R
the nuclear radius. Since R ∝ A1/3 and Z is roughly
proportional to A, the Coulomb energy is roughly proportional to
A5/3. On the other hand,
the total binding energy is proportional to A, which means that the relative
importance of the repulsive electrostatic energy increases with increasing mass
number as A2/3.
See also: → coulomb; → energy.
