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!