THE FIELDS OF MOVING CHARGES — Edward Purcell & David Morin
Physics — E&M · laminated-conductor
Problem
Laminated conductor **
A laminated conductor is made by depositing, alternately, layers of silver 100 angstroms thick and layers of tin 200 angstroms thick (1 angstrom =10−10 m). The composite material, considered on a larger scale, may be considered a homogeneous but anisotropic material with an electrical conductivity σ⊥ for currents perpendicular to the planes of the layers, and a different conductivity σ∥ for currents parallel to that plane. Given that the conductivity of silver is 7.2 times that of tin, find the ratio σ⊥/σ∥.