Temperature coefficient of resistance

Thread Starter

Donnybri

Joined Oct 3, 2009
1
R2=R1[1+(alpha)(t2-t1)]

Using the above equation, I need to find the maximum workable temperature (t2) of a circuit which contains a relay coil (whos resistance does not change with temp), and two different metal conductors.

I have found the resistance of the circuit at 20 degC using the two different temperature coefficients.

1. How do I fit the two different temperature coefficients into alpha in the equation?

2. and, as R1 contains two different resistances which will rise with temperature at different rates, how do I split them?

Any help appreciated.
Thanks in anticipation.

edit: Has this got everyone as perplexed as I am?

edit 2: I'm getting a bit desperate now!!
 
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