something about α ( temperature coefficient of resistivity )?

Question

hi
i wanted to know why "temperature coefficient of resistivity" (α)rises in high tempretures ?
tungesten α ( 0-100 C ) : 0.0046
but :
T1 = 20 ˚C R1 = 5.5
T2 = 3227 ˚C R2 = 108.5
then the α would be around 0.0058

Answer 1

Because the unfortunate fact is that almost *nothing* in the real world is truly 'linear' ☺
The temperature coefficient of resistivity is more non-linear for some materials than others, but it's non-linear for *all* conductors and, in fact, is negative for some and positive for others. This is a particular problem in very high-accuracy electronic circuits that must operate over wide ranges of temperature (read 'deep space instrumentation'). But it turns out that by 'matching' different materials, some with positive tempcos and some with negative, it is possible to get resistance elements that have a nearly zero overall tempco.

HTH ☺

Doug