Algebra II
posted by Marie on .
If 750 m of 3.00mmdiameter wire has a resistance of 27.6, what length of similar wire 5.00 mm in diameter will have the same resistance?

R = kL/d^2
Find k:
27.6 = k(750)/9
k = 0.3312
So, now we find the new L:
27.6 = .3312L/25
L = 2083.3 mm
Makes sense. The diameter has almost doubled, so the resistance is about 1/3 of what it was. (9/25 actually)
Note that 750 * 25/9 = 2083.3