Hall scattering factor ($r_H$)

For one positive carrier population, define $r_H$ by $R_H=r_H/(ep)$ with $e>0$. Different statistical averages of energy-dependent scattering affect hall conductivity and longitudinal electrical conductivity, so $r_H$ need not be one. The measured Hall mobility is ${\mu }_H=\sigma R_H=r_H{\mu }_{\mathrm{drift}}$. Multiple charge carriers require a more general model even before such a correction is made.