Page 276 - Electrical Properties of Materials

258 Dielectric materials

[Hint: Write down the equation of motion for an electron, 10.11. Using the data for KCl given in Exercise 5.4 estimate
taking into account viscous friction (proportional to velocity) a frequency at which the dielectric constant of KCl will relax
and restoring force (proportional to displacement). Solve the to a lower value.
equations for a driving force of eE exp(–iωt). Remember that
polarization is proportional to displacement and finally find [Hint: Around the equilibrium value the force is propor-
the real and imaginary parts of the dielectric constant as a tional to displacement (to a first approximation), whence a
function of frequency.] characteristic frequency can be derived.]