# Calculate the resistance at 18 Celsius

1. Oct 25, 2005

### kEEhOLDEN

cant do this question, well i cant figure out what im supposed to do, whether its a thermistor or not, i worked out the inductance, but im not sure what to do after that, heres the question

Calculate the resistance at 18 celcius of a 5cm diameter close-wound, single layer coil of 1000 turns of copper wire of 0.1mm diameter.

what would its approximate resistance be at a temperature of 100 celcius???

thanks

2. Oct 25, 2005

### Staff: Mentor

Doesn't sound like they want the inductance -- sounds like they are asking for the resistance of the coil at two different temperatures. You need the rho of copper, and it's tempco (temperature coefficient). The total resistance R = rho*L/A, where L = total length, and A = area (of the wire cross-section in your case).

If you have a chem table book or EE reference book handy, you can find the info in there. Or easier is to just google the following:

+copper +resistivity +temperature

and the first hit you get will give you what you need:

http://hypertextbook.com/facts/2004/BridgetRitter.shtml

BTW, I'm kind of a newbie to the PF forums, so I just learned recently that questions like this are supposed to be posted in the HW forums. So now I try to check out the HW question forums to see if I can be of help.

3. Oct 25, 2005

### kEEhOLDEN

thanks thats very helpful, i jus joined the forums, that was my first post, so i havent a clue what is going on in here anyways, cheers