# Homework Help: Calculating Resistance(not at RT) using the Resistivity Formula

1. Jul 17, 2006

### Jozers

For my coursework "Resistance in a Wire" I used the R=ρL/A formula to predict what resistance I should get. Yet, as it was a hot day when i did the experiment the Room Temperature was not ambient but 28°C. Therefore my there was a small systematic error with my results (they were consistantly higher than predicted). I wish to show that this error was due to the temperature and would like to use the formula

R=(L/A)ρ=(L/A)ρ0(α(T - T0)+1)

I'm think that ρ0 is the residual resistance, α is the thermal resistance and T0 is room temperature. Could someone just clarify this? And where could i find out these properties for "Constantan" Alloy? As iv'e been unsuccessful of find these on the internet.

I would also be useful if someone knows of and example (which include the Temp. part) explaining how to use this formula, it should be easy to figure out but any help would be great.

Thanks
Jozers

Last edited: Jul 17, 2006
2. Jul 17, 2006

### Astronuc

Staff Emeritus
Last edited by a moderator: May 2, 2017
3. Jul 17, 2006

### Jozers

Thank you Astronuc.

Last edited: Jul 17, 2006