Question

A copper wire has a resistance of 85Ω at 150C. Calculate its resistance at 900C. Assuming the temperature coefficient resistance of copper to be 0.0043/0C,

Answer 1

At 15°C:

$$R_1=R_0(1+\alpha T_1),\\\space\\ R_0=\frac{R_1}{1+\alpha T_1}.$$

Find the resistance at 90°C:

$$R_2=R_0(1+\alpha T_2),\\\space\\ R_2=\frac{R_1}{1+\alpha T_1}(1+\alpha T_2)=110\Omega.$$