Why does heat affect resistors?

[merr]

I'm doing coursework and i know it's dumb but i just can't remember how heat is supposed to affect resistors *heh* If someone could give me a quick explanation, it's not for the main part of the coursework, it's just a factor i have to controll in another experiment, but i can't remember why i have to controll it! D:

 

[Hootenanny]

http://www.google.co.uk/search?q=resistors+heat

 

[merr]

thanks, one more question, why would that affect the voltage in a circuit with a resistor?

 

[Hootenanny]

thanks, one more question, why would that affect the voltage in a circuit with a resistor?

Think about Ohms Law.