# Unit Of Resistivity

1. Mar 9, 2013

### Bashyboy

Hello,

In my lab report, I am trying to discuss what the units of resistivity mean. For instance, the unit of speed m/s second can be described as the time it takes to travel 1 m; specifically, 50 m/s would say that it would take 1 s to travel 50 m, or, we travel 50 m every second.

Could someone possibly help me with this?

2. Mar 9, 2013

### Bashyboy

I am having difficulty with this one passage:

One way to describe a material (any material) is by its RESISTIVITY. This is the amount of resistance present in a piece of the material OF STANDARD DIMENSIONS.

What exactly are standard dimensions?

3. Mar 9, 2013

### trollcast

Standard dimensions means 1m cubed if the units are Ωm or 1cm cubed if the units are Ωcm and so on.

4. Mar 9, 2013

### Staff: Mentor

If you have a cylindrical bar of resistive material, as you might expect, its electrical resistance will be proportional to the length of the bar, and inversely proportional to its cross sectional area. The constant of proportionality is the resistivity, which is a property of the material. So, Ω=ρL/A, and the units of ρ are thus ohm-meters.