Relaxation properties of fields and circuits

Electromagnetic fields tend to be in the lowest energy state consistent with the constraints of the system. This relaxation property of fields is discussed from the viewpoint of a variational principle. The study encompasses many closely related theorems, widely dispersed throughout the literature, whose origin is traced to a single variational principle derivable from Maxwell´s equations. Kirchhoff´s voltage law is also shown to follow from the variational principle. This leads to an interesting interpretation of a fundamental law in circuit theory, and also permits the derivation of the principle of conservation of flux.