Question
Classify metals, conductors and semiconductors.
✓
Answer
On the basis of conductivity : On the basis of relative value of electrical conductivity ( $\sigma$ ) or resistivity $( \rho=$
$1 / \sigma$ ) solid materials are classified as follows :
$(i)$ Metals : Their resistivity is very low $($or conductivity is very high$).$
$\rho \sim 10^{-2}-10^{-8} \Omega m$
$\sigma \sim 10^2-10^8 Sm^{-1}$
$(ii)$ Semiconductors : Their resistivity or conductivity is between metals and insulating materials.
$\rho \sim 10^{-5}-10^6 \Omega m$
$\sigma \sim 10^5-10^{-6} Sm^{-1}$
$(iii) $ Insulators : Their resistance is very high $($or conductivity is very low$).$
$\rho \sim 10^{11}-10^{19} \Omega m$
$\sigma \sim 10^{-11}-10^{-19} Sm^{-1}$
The values of $\rho$ and $\sigma$ given above are only indicative of the order value and may go outside the given range.
$1 / \sigma$ ) solid materials are classified as follows :
$(i)$ Metals : Their resistivity is very low $($or conductivity is very high$).$
$\rho \sim 10^{-2}-10^{-8} \Omega m$
$\sigma \sim 10^2-10^8 Sm^{-1}$
$(ii)$ Semiconductors : Their resistivity or conductivity is between metals and insulating materials.
$\rho \sim 10^{-5}-10^6 \Omega m$
$\sigma \sim 10^5-10^{-6} Sm^{-1}$
$(iii) $ Insulators : Their resistance is very high $($or conductivity is very low$).$
$\rho \sim 10^{11}-10^{19} \Omega m$
$\sigma \sim 10^{-11}-10^{-19} Sm^{-1}$
The values of $\rho$ and $\sigma$ given above are only indicative of the order value and may go outside the given range.
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