- #1
Northbysouth
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Homework Statement
What diameter must a copper wire have if its resistance is to be the same as that of an equal length of aluminum wire with diameter 3.94mm?
Give your answer in mm
Homework Equations
R = ρL/A
where A is the cross sectional area, L is the length and ρ resistance of the material
ρCopper = 1.72x10-8 Ωm
ρAluminum = 2.82x10-8 Ωm
The Attempt at a Solution
So I knew that Rcopper = RAluminum
(1.72x10-8Ωm)(L)/Acopper = (2.82x10-8Ωm)(L)/(0.00394m)
A = 0.00240 m
A = πr2
r = 0.027657 m
diameter = 55.31499 mm
But the system says its wrong and I don't see where I've gone wrong.