Two rods of different materials having coefficients of thermal expansion I _ 1 , x_ 2 and…

Two rods of different materials having coefficients of thermal expansion \(\mathbf{I}_{1}\), \(x_{2}\) and Young's moduli Y₁, Y₂ respectively are fixed between two rigid massive walls. The rods are heated such that they undergo the same increase in temperature. There is no bending of the rods. If \(\mathbf{I}_{1}\): \(x_{2}\) = 2 : 3, the thermal stress developed in the two rods are equal provided Y₁ : Y₂ is equal to