Lag1989 problem number 18.48

A flat capacitor consists of two identical metal disks, the space between them is filled with a homogeneous weakly conducting medium with a dielectric constant and conductivity. The distance between the inner surfaces of the disks is L. Between the capacitor plates, the voltage U = Umax · cos (ω · t) is maintained. Ignoring the edge effects, find the modulus of the magnetic field H between the capacitor plates at a distance r from their axis.