# Physics

posted by
**Kevin** on
.

What length of #22 B&S gauge copper wire is needed to make a resistance of 500 ohms?

This is what I came up with but don't think it is correct. looked up diameter for #22 gauge wire = .643 mm and converted to m 6.46 * 10^-4.

Used Eq. A = (pi)(d^2)/4 =>

A = (pi)(6.43 * 10^-4)^2/ = 3.24 * 10^-7 m

Then I used R=(p)l/A and rearranged so now its (R)(A)/p = l

p was given in a chart in my book for copper wire as p = 1.72*10^-8 so here is what I did and the answer I got for l

(500)(3.24*10^-7)/1.72*10^-8) =

9.42*10^3

to me this seems like a very long piece of wire so I think I did something wrong