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Classify solids on basis of electrical conductivities. |
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Answer» Solution :Solids exhibit conductivities from `10^(-20) ` to `10^7 "ohm"^(-1) m^(-1)`. This are classified as : (i) Conductors (ii) Insulators and (iii) Semi conductors (i) Conductors : The solids with conductivities ranging between `10^4` to `10^7 ohm^(-1)m^(-1)` are called conductors. Metals have conductivities in the order of `10^7 "ohm"^(-1) m^(-1)` and hence they are good conductors. (ii) Insulators : These are the solids with very low conductivities ranging between `10^(-20)` to `10^(-10) ohm^(-1) m^(-1)`. EX. : Wood, Plastics etc. (iii) Semiconductors : These are the solids with conductivities in the intermediate range from `10^(-6)` to `10^4 "ohm"^(-1)m^(-1)` . The conductivity of semiconductor is mainly because of defects or impurities present in it. The conduction of electricity in metals and semiconductors is explained by Bond Theory. Certain transition metal oxides show differences in electrical properties :  `ReO_3` has appearance and conductivity SIMILAR to copper. |
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