1. The problem statement, all variables and given/known data 2. Relevant equations [itex]\Delta R[/itex]/ R0 = [itex]\alpha[/itex] [itex]\Delta T[/itex] which goes down to : r-r0 /r0 = alpha (T-T0) r/r0 = alpha T +1 3. The attempt at the solution Hi there, I'm on a verge of mental breakdown. I have spent over 2 a4- sheets on figuring out how to get 't'. I have found out the value r/ro... however the part to find 't' has been daunting... I am aware of the expression within the bracket being a quadratic equation,hence two solutions of 't'... but what becomes of the value of r/r0 ? Thanks for your help in advance.