This paper was written to show to undergraduate students of Physics and Engineering how to estimate the Foucault or eddy currents, in conductors. We begin with a brief discussion about the boundary conditions at the interface of two different medias with respective parameters ε, µ and σ, which must be satisfied by both static and time dependent electromagnetic fields. Afterwards, using the Maxwell equations, we calculate the eddy currents which are induced in a plane metallic conductor (either paramagnetic or diamagnetic) when a time variable magnetic field B (t) produced by a long solenoid of circular cross section is applied upon it.
Foucault; Eddy current; magnetic brake; magnetic levitation
