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:

$0.47Sm^{-1}$ $5.18 Sm^{-1}$ $2.12 Sm^{-1}$ $1.09 Sm^{-1}$

$2.12 Sm^{-1}$

The electrical conductivity of germanium, $σ=\frac{1}{ρ}=e(μ_en_e+μ_hn_h)$ $=(1.6×10^{-19})[0.36 0.17](2.5×10^{19})$ $=2.12 Sm^{-1}$