A wire is 1.0m long, 0.2mm in diameter and has a resistance of $10Ω.$ Calculate the resistivity of its material?
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l = 1m
$\text{r}=\frac{\text{d}}{2}=\frac{0.2}{2}\text{mm}=0.1\text{mm}=0.0001\text{m}$
R = 10 ohm
We know that,
$\text{R}=\text{P}\frac{\text{I}}{\text{A}}$
$\text{P}=\frac{\text{RA}}{\text{I}}$
$=\frac{10\times\pi\times(0.0001)^2}{1}$
$=31.4\times10^{-8}\Omega\text{m}$
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