Calculate the resistance of an aluminium cable of length $10\ km$ and diameter $2.0\ mm$ if the resistivity of aluminium is $2.7\times10 Ω\ \text{m}.$
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$I = 10km = 10000m$
$d = 2mm$
$r = 1mm = 10^{-3}m$
$\rho=2.7\times10^{-8}\Omega\ \text{m}$
$\text{R}=\rho\frac{\text{I}}{\text{A}}$
$=2.7\times10^{-8}\times\frac{10000}{3.14\times(10^{-3})^2}$
$=0.859\times10^2\Omega$
$=86\Omega$
$d = 2mm$
$r = 1mm = 10^{-3}m$
$\rho=2.7\times10^{-8}\Omega\ \text{m}$
$\text{R}=\rho\frac{\text{I}}{\text{A}}$
$=2.7\times10^{-8}\times\frac{10000}{3.14\times(10^{-3})^2}$
$=0.859\times10^2\Omega$
$=86\Omega$
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