Two protons in a hydrogen atom are separated by about 10−10m. Which statement correctly explains why the electromagnetic interaction, and not the strong nuclear force, determines the energy levels of the atom?
(a) The strong nuclear force is intrinsically weaker than the electromagnetic force, so it cannot influence atomic structure.
(b) The strong force only acts between quarks inside a single proton or neutron, not between separate protons, so it has no effect at atomic distances.
(c) The range of the strong nuclear force is much smaller than 10−10m, so its effect is negligible at atomic distances.
(d) Beyond about 10−12m the strong nuclear force becomes repulsive, hence it does not contribute to the hydrogen-atom energy levels.