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

i need to find the radius of a copper wire given the following data:

resistivity is 0.25 ohm meter

length of wire is 200 m

2. Relevant equations

roe=RS/I

roe=resistivity

R= resistance of material

S=cross sectional area

I= length of specimen

3. The attempt at a solution

i was looking at the equation and noticed i dont have any value for the resistance of the copper, so i looked it up online and it said: 0.00000001678 ohm.m. since i have 200m of wire i multiplied it by 200. so into the equation with everything:

0.25=3.356x10^-6 x s/200 meters

rearranging for the cross section area:

s= 21222410.9

although it doesnt say in the question, i assume that the cross section area of copper wire is circular. so i use the area of a circle to find the radius:

A= pi r^2

r= 2599 m

i dont know about you but this doesnt seem right, to have a wire with radius of 2.5 kilometers. im stuck at what to do, my only guess is that the resistance value is wrong and i know there is and equation for resistance:

resistance= resistivity x length/area

i have the resisivity and the length, but what would i use for area?

help!

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# Homework Help: How to find the radius of copper wire given resistivity values

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