Mobilities of electrons and holes in a sample of intrinsic germanium at room temperature are $0.36m^2 / Vs$ and $0.17m^2 / Vs$. The electron and hole densities are each equal to $2.5×10^{19}m^3$. The electrical conductivity of germanium is:

$2.12 Sm^{-1}$

The electrical conductivity of germanium,

$σ=\frac{1}{ρ}=e(μ_en_e+μ_hn_h)$

$=(1.6×10^{-19})[0.36 0.17](2.5×10^{19})$

$=2.12 Sm^{-1}$