1. Apparatus for use in electric tomography comprising: a coupling medium for receiving an object to be examined; a plurality of electrodes disposed in communication with said coupling medium and arranged in a three dimensional array generally surrounding the object to be examined; multiplexing and measuring means for applying electric voltages at selected first pluralities of electrodes and simultaneously measuring electric currents including non-straight line currents at corresponding selected second pluralities of electrodes in a desired sequence; computation means coupled to said multiplexing means for initially estimating the values of the electrical properties at a multiplicity of locations in the object to be examined, said locations being arranged in a three dimensional imaginary grid defined in the object to be examined and subsequently correcting the initially estimated values of the electrical properties at each of said multiplicity of locations by solving an inverse Laplace equation using the applied electric voltages and electrical current measurements provided by said multiplexing and measuring means by an iterative process; and means for providing a visible tomographic representation of the values of the electrical properties at each of said multiplicity of locations as determined by said computation means.