When a rod is healed but prevented from expanding, the stress developed is independent of

lt=l0(1+αt)The extension in length is given by 1=lt−l0=l0αtIf the same rod of length 1o is subjected to stress along its length, then extension in length can be calculated by Hooke's law.Y= stress  strain = stress l/l0=l0 stress l∴       l=l0 stress Y           ....(2)If the rod is prevented by expanding, we have                    l0αt=l0 stress Y∴Stress = Y  α t (independent of Io)