A steel rod of length L and diameter D, fixed at both ends, is uniformly heated to a temperature
rise of $\left ( \Delta \right )$T. The Young’s modulus is E and the coefficient of linear expansion is ‘$\alpha$’. The thermal
stress in the rod is
(a) 0 (b) $\alpha \Delta$T
(c) E$\alpha \Delta$ t (d) E $\alpha \Delta$ TL