I came across a question recently:
A wire has a resistance of 2.1 ohm at 300 K, and 2.7 ohm at 373 K. What is the temperature coefficient of resistance of the metal?
I tried by simply putting the formula R2 = R1 (1 + A(T2 - T1)), and got the answer as 2/511.
But when I did -
R2 / R1 = Ro (1 + A(T2 - To) / Ro (1 + A(T1 - To)
taking To as 273 K, I was getting 2/457.
This got me wondering, I can take any value of To and get a different answer. Why is this so, since I am simply taking out the ratio here?