# Homework Help: Resistivity/Temperature problem

1. Feb 28, 2006

### skiboka33

I'm stuck on a problem. It involes the temperature/resistivity relationship formula:

$$\rho = \rho_0 (1 + \alpha (T - T_0))$$

In the problem I am given the value of $$\alpha$$ and $$\rho_0$$ and I am told that these values were found at 20 degrees Celcius. I am asked to find the coefficient $$\alpha^'$$ at 0 degrees.

So that: $$\rho = \rho_0^'$$$$(1 + T$$$$\alpha^'$$$$)$$

Were $$\rho_0^'$$ is the resistivity at 0 degrees.

Seems like I need more information after equating both equations. I think I should be able to show alpha prime as a fuction soley of alpha (independant of everything else) is this correct? any help would be appreciated, thanks!

2. Feb 28, 2006

### stunner5000pt

I will try to answer this
there must be some other info you are given about the resisitivitiy (pho) at T = 0K?
Could you type out the question as it appears, maybe there is a clue in the wording of hte problem.

3. Feb 28, 2006

### skiboka33

Sure,

The temperature coefs of resistivty on Table 27 (in the textbook) were determined at 20 degrees C. What would they be at 0 degrees C. Calculate the coefs for silver, copper and gold (all in table, resistivity is also in the table for each). Note that the temperature coefficient of resistivity at 20 degrees C satisfies:
$$\rho = \rho_0 (1 + \alpha (T - T_0))$$ where rho(0) is the resistivity of the material at T(0) = 20 degrees. The temp coef of resistivity, alpha prime at 0 degress must satisfy [the equation in the above post, with T(0) = 0, p(0)' and alpha prime insterted] where p(0)' is the resistivity of the material at 0 degrees C.

That's it, thanks.