Maharashtra BoardEnglish MediumSTD 12 ScienceChemistrySolid State3 Marks
Question
How are solids classified according to electrical conductivity?
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Answer
According to electrical conductivity, solids are classified as follows :
$(1)$ Conductors :
The solids having electrical conductivity in the range of $10^4$ to $10^7$$Ohm ^{-1} m ^{-1}$ are called conductors.
The examples of conductors are metals and electrolytes.
Electrical conductivity in metals is due to free movement of electrons while electrolytes conduct electricity due to migration ions.
$(2)$ Insulators :
Solids having very low electrical conductivity in the range of $10^{-20}$ to $10^{-10} \ Ohm ^{-1} m ^{-1}$ are called insulators.
The examples of insulators are nonmetals and molecular solids.
$(3)$ Semiconductors :
Solids having conductivity in the range of $10^{-6}$ to $10^4 \ Ohm^{-1}m^{-1}$ are semiconductors.
The conductivity range is intermediate between conductors and insulators.
The examples of semiconductors are silicon and germanium.
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