Question

The temperature coefficient of resistivity of carbon is - 0.0005/C°.if the resistor is made of graphite has a resistance of 5 k$\Omega$ at 20° find the resistance at 27°

Answer 1

$$R(t_2)=R(t_1)(1+\alpha(t_2-t_1))$$

$$R(27)=R(20)(1+\alpha(27-20))$$

$$R(27)=5000\:\Omega(1+(- 0.0005)*7)=4983\:\Omega$$