(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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

2. Relevant equations

R = ρL/A

where A is the cross sectional area, L is the length and ρ resistance of the material

ρ_{Copper}= 1.72x10^{-8}Ωm

ρ_{Aluminum}= 2.82x10^{-8}Ωm

3. The attempt at a solution

So I knew that R_{copper}= R_{Aluminum}

(1.72x10^{-8}Ωm)(L)/A_{copper}= (2.82x10^{-8}Ωm)(L)/(0.00394m)

A = 0.00240 m

A = πr^{2}

r = 0.027657 m

diameter = 55.31499 mm

But the system says its wrong and I don't see where I've gone wrong.

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# Diameter of copper wire to have same resistance as equal length aluminum wire

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