What is the resistivity of a wire when voltage increases?

[Jaccobtw]

Homework Statement

A wire has a uniform cross sectional area of 1cm^2 and a length of 1m. When the potential difference across the wire is increased by 16V, the current increases by 2A. What is the resistivity of the wire?

Relevant Equations

$$R = \frac{l}{\sigma A}$$

Divide volts by current to get resistance which is 8. Multiply both sides by 8 and sigma to get:

$$\frac{1m}{8\Omega\times10^{-4}m^2} = 1250$$

But this answer seems to be way off. How did I go wrong? Thanks

 

[Orodruin]

First you are lacking units. Units are important.

Second, you have computed conductivity, not resistivity.