We present a short analysis of the electric transient response when a steady current in a frequency dispersive medium is interrupted. The model is a homogeneous host rock medium with a loading of spheroidally shaped metal ore grains. The latter can have a polarizable interface with the adjacent electrolyte. It is shown that the rate of decay of the electric field is more rapid for the smaller particles. Also, there is an optimum particle size if the area under the decay curve is to be maximized.