# What diameter wire should be used for particular resistance?

1. Oct 3, 2009

### Kastner86

1. The problem statement, all variables and given/known data

If 49 m of nichrome wire is to have a resistance of 16.0 ohms at 20 degrees Celcius, what diameter wire should be used?

2. Relevant equations

R = $$\rho$$ x L / A

A = $$\Pi$$ d^2 / 4

3. The attempt at a solution

well i know what i'm looking for, that is d (diameter)

and d = $$\sqrt{}$$(4$$\rho$$L/$$\Pi$$R)

I don't know what the value of $$\rho$$ is.

I know it is supposed to be the resistivity of the material, at a certain temperature, but I have no idea how to include it in the equation.