alleryMaterials are classified as conductors, semiconductors and insulators by resistivity. Metals fall in which range of resistivity?
A$10^{-8}\ \Omega\text{m}$ to $10^{-6}\ \Omega\text{m}$
B$10^{6}\ \Omega\text{m}$ to $10^{8}\ \Omega\text{m}$
Cabout $10^{12}\ \Omega\text{m}$
Dabout $10^{18}\ \Omega\text{m}$
Answer & Solution
Correct answer: A. $10^{-8}\ \Omega\text{m}$ to $10^{-6}\ \Omega\text{m}$
1. Resistivity rises in the order conductors < semiconductors < insulators.
2. Metals have the lowest resistivities, from $10^{-8}$ to $10^{-6}\ \Omega\text{m}$.
3. Insulators are about $10^{18}$ times larger, so D describes insulators.
4. The mid-range values (C) correspond to poorer conductors, not metals.
_Source: syllabus Physics Ch 3 "Current Electricity", p.9_
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