Classify solid substances based on electrical conductivity and resistivity.

(N/A) On the basis of the relative values of electrical conductivity $(\sigma)$ or resistivity $(\rho = 1/\sigma)$,solids are classified into three categories:
$(1)$ Metals: They possess very low resistivity or high conductivity.
$\rho \sim 10^{-2} \Omega \cdot m$ to $10^{-8} \Omega \cdot m$
$\sigma \sim 10^{2} \text{ S} \cdot m^{-1}$ to $10^{8} \text{ S} \cdot m^{-1}$
$(2)$ Semiconductors: They have resistivity or conductivity intermediate between metals and insulators.
$\rho \sim 10^{-5} \Omega \cdot m$ to $10^{6} \Omega \cdot m$
$\sigma \sim 10^{5} \text{ S} \cdot m^{-1}$ to $10^{-6} \text{ S} \cdot m^{-1}$
$(3)$ Insulators: They have high resistivity or low conductivity.
$\rho \sim 10^{11} \Omega \cdot m$ to $10^{19} \Omega \cdot m$
$\sigma \sim 10^{-11} \text{ S} \cdot m^{-1}$ to $10^{-19} \text{ S} \cdot m^{-1}$
The values of $\rho$ and $\sigma$ given above are indicative of magnitude and can vary outside these ranges. Relative values of resistivity are not the only criteria for distinguishing metals,insulators,and semiconductors.