Two rods of different metals having the same area of cross section A are placed between the two massive walls as shown in Fig. The first rod has a length $l$  coefficient of linear expansion ${\alpha }_1$  and Young’s modulus $Y_1$ . The corresponding quantities for second rod are  $l,{\alpha }_{2}and{Y}_2$. The temperature of  both the rods is now raised by  $t^{0}C$.