Classify a solid substance based on electrical conductivity and resistivity.

Explanation

On the basis of the relative values of electrical conductivity `(sigma)` or resistivity `(rho=(1)/(sigma))`, the solids are classified by three ways.
(1) Metals : They posses very low resistivity or high conductivity.
`rho~10^(-2) Omega m " to " 10^(-8)Omega m`
`sigma ~ 10^(2)Sm^(-1)" to " 10^(8)Sm^(-1)`
(2) Semiconductors : They have resistivity or conductivity intermediate of metals and insulators.
`rho~10^(-5) Omega m " to " 10^(6)Omega m`
`sigma ~ 10^(5)Sm^(-1)" to " 10^(-6)Sm^(-1)`
(3) Insulators : They have high resistivity or low conductivity.
`rho~10^(11) Omega m " to " 10^(19)Omega m`
`sigma ~ 10^(-11)Sm^(-1)" to " 10^(-19)Sm^(-1)`
The values of `rho` and `sigma` given above are indicative of magnitude and could well go outside the range as well.
Relative values of the resistivity are not the only criteria for distinguishing metals, insulators and semiconductors from each other.