Two rods of different materials having coefficients of linear expansion ${\mathrm{\alpha }}_1\text{ and }{\mathrm{\alpha }}_2$ and Young's moduli, Y₁ and 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 rods. If ${\mathrm{\alpha }}_1/{\mathrm{\alpha }}_2=2/3$, then the thermal stresses developed in the two rods are equal, provided Y₁/Y₂ is equal to

• A

  2:3

• B

  1:1

• C

  3:2

• D

  4:9