Answer Happy

Problem 10.4. The current in a silicon wafer , Two cylindrical copper electrodes of radius a are oriented normal to a silicon wafer of thickness t, and their axes are separated by the distance b. The electrodes are embedded in the wafer to a depth t – in other words, they go completely through the wafer. The lateral dimensions of the wafer are large compared to b and may be considered as infinite. Taking the conductivity of silicon to be o, find the current between the electrodes when their potential difference is Að. > Hint: A pair of opposite line charges produces cylindrical equipotential surfaces, just as a pair of point charges produces spherical equipotential surfaces. The easiest way to find the electrostatic potential in this problem is to mimic it by replacing the pair of cylinders by a pair of appropriately placed line charges with the appropriate line charge densities.