If 750 m of 3.00-mm-diameter wire has a resistance of 27.6, what length of similar wire 5.00 mm in diameter will have the same resistance?

Answer 1

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

Answer 2

What is that k means??is it rho?