1. The problem statement, all variables and given/known data the difference in length between an aluminium rod and a copper rof at 0 degreeC is 2cm. If they have the same difference in length at any temperature difference, what are the length of the 2 rods at 0 degreeC.? Al - expansivity = 20*10^-4 K^-1 Cu- expansivity= 15*10^-6 K^-1 2. Relevant equations alpha inversely proportional to the initial length 3. The attempt at a solution i divided the expansivities of the two rods and made it equal to the ratio of theinitial lengths of the rods and got the length of the Al rod as 6 cm and the Cu rod as 8 cm. Which is the answer the school teacher said is correct. I can't understand why it can't be the other way around.