Resistance:

$\overline{){\mathbf{R}}{\mathbf{=}}\frac{\mathbf{\rho}\mathbf{L}}{\mathbf{A}}}$, where ρ is the resistivity, L is the length, and A is the cross-sectional area of the wire.

Cross sectional area:

$\overline{){\mathbf{A}}{\mathbf{=}}{\mathbf{\pi}}{{\mathbf{\left(}}\frac{\mathbf{d}}{\mathbf{2}}{\mathbf{\right)}}}^{{\mathbf{2}}}}$

In household wiring, copper wire 2.05 mm in diameter (12 gauge) is often used. Find the resistance of a 24.0 m length of this wire. Note the resistivity of copper is 1.72*10^{-8 }Wm.

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