Question

A 15.00cm long bimetal strip is aluminum on one side and copper on the other. If the two metals are the same length at 20.0◦C, how long will each be at 800.◦C?

Answer 1

For the strips expanding at increased temperature, we have

$$l_\text{Cu}=l_0(1+α_\text{Cu}Δt)=15.20\text{ cm},\\ l_\text{Al}=l_0(1+α_\text{Al}Δt)=15.26\text{ cm}.$$

The linear expansion temperature coefficients for copper is 16.7·10^-6 1/°C, for aluminum it is 22·10^-6 1/°C. The temperature difference between 800°C and 20°C is 780°C.