The basic structure of the classical electromagnetism is used as a means to study the strong interaction. The strong coupling constant and the strong field (expessed in terms of an equivalent electric field) inside the nucleon (proton or neutron) are estimated. It is also evaluated the vacuum pressure on the boundary of the nucleon. Quark confinement is briefly discussed. Simplified versions of the MIT bag model are also considered in the present treatment.
strong interaction; quark confinement; bag model
