Question

What is the resistance of a 5.9-m length of copper wire 1.2 mm in diameter? The resistivity of copper is 1.68×10−8Ω⋅m.

Answer 1

given that

length of the resistance l = 5.9m

diameter of copper wire d = 1.2 mm

so radius of copper wire r = d/2; r = 0.6 mm = 0.0006 m

resistivity of copper = 1.68×10⁻⁸Ω⋅m

formula :

$R = \frac{\rho l}{A}$

where R = resistance ; rho =resistivity; l = length of the wire; A = area of cross section.

here area of cross section $A = \pi r^{2}$

therefore A = 3.14 x 0.0006 x 0.0006

A = 0.0000011304 m ²

substitute the value in $R = \frac{1.68 \times 10^{-8} \times 5.9}{0.0000011304}$

R = 8.77 x 10^-2 ohm