# Homework Help: Finding Length and Diameter Of A Wire

1. Mar 14, 2013

### Bashyboy

1. The problem statement, all variables and given/known data
Suppose you wish to fabricate a uniform wire from 2.00 g of copper. The wire is to have a resistance of* R = 0.480 Ω*and all the copper is to be used.

2. Relevant equations

3. The attempt at a solution

In the problem, they suggest using this relationship for resistance $R=\rho A l$. How did they get that? From my understanding, resistance is $R = \rho \frac{l}{A}$

2. Mar 14, 2013

### ehild

You are right, R=ρL/A.

ehild

3. Mar 14, 2013

### Staff: Mentor

The mass is $M=Ald$, where d is the density.