# Homework Help: Temperature Coefficient of Resistivity

1. Apr 30, 2007

### Boozehound

A coil of wire has a resistance of 37.800 Ω at 27.800 °C and 44.400 Ω at 56.000 °C. What is the temperature coefficient of resistivity? Do not enter units.

Equation: R=R0[1+α(T-T0)]

then i plugged in number to make the equation look like this:

44.400=37.800[1+X(56.000-27.800)]

and i solve for X and i get X=.0402 and its wrong...

anyone see something i dont?

2. Apr 30, 2007

### hage567

3. Apr 30, 2007

### Boozehound

44.400=37.800[1+X(56.000-27.800)

44.400=37.800[1+X(28.2)

44.400=37.800[1+28.2X]

44.400=37.800[29.2X]

1.1746=29.2X

.0402=X

those are the steps i used...im not too sure about what to do with the 1+X part but that might be where im going wrong.

Last edited: Apr 30, 2007
4. Apr 30, 2007

### hage567

You can't add the 1 to the 28.2, since the units are not the same (it doesn't make sense to do that). You must go

(44.4/37.8) - 1 = 28.2X

in the next step to isolate X.

5. Apr 30, 2007

### Boozehound

ah! yeah now that you say it that doesnt make sense.. thank you very much!

6. Apr 30, 2007

### hage567

You're welcome.