  In this report we discuss static and time dependent electric fields in
detector geometries with an arbitrary number of parallel layers of a given
permittivity and weak conductivity. We derive the Green's functions i.e. the
field of a point charge, as well as the weighting fields for readout pads and
readout strips in these geometries. The effect of 'bulk' resistivity on
electric fields and signals is investigated. The spreading of charge on thin
resistive layers is also discussed in detail, and the conditions for allowing
the effect to be described by the diffusion equation is discussed. We apply the
results to derive fields and induced signals in Resistive Plate Chambers,
Micromega detectors including resistive layers for charge spreading and
discharge protection as well as detectors using resistive charge division
readout like the MicroCAT detector. We also discuss in detail how resistive
layers affect signal shapes and increase crosstalk between readout electrodes.
