Abstract :
Material inhomogeneities, defective
materials or fractured solids address the notion
of configurational force. In electromagnetic deformable
bodies this force also depends upon the electromagnetic
potentials, which unfortunately
are not uniquely defined. In electrostatics the problem
of uniqueness is scarcely relevant, as only the
scalar potential plays a role. Thus, dielectrics are
adequately described in this context, even in the
presence of a crack-line. In electrodynamics also
the vector potential plays a prominent role and the
lack of uniqueness of the electromagnetic potentials
cannot be disregarded. The problem of solving
this indeterminacy for the quantities of interest
appeals to additional conditions, the gauge conditions.
Gauge transformations, which leave invariant
the Maxwell equations and the balance of
momentum in material form, are here examined.
In configurational mechanics of electromagnetic
solids, a possible gauge dependent quantity is the
material momentum, which seems to be related to
some extent to supercurrents in deformable superconductors.
