Question

Two ends of a conducting rod of varying cross-section are maintained at ${200}^{\circ }\text{C}$ and $0^{\circ }\text{C}$ respectively. In staedy state

• A. $\text{temperature difference across}AB\text{and}CD\text{are equal}$
• B. $\text{temperature difference across}AB\text{is greater than that of across}CD$
• C. $\text{temperature difference across}AB\text{is less than that of across}CD$
• D. $\text{temperature difference may be equal or different depending on the thermal conductivity of the rod}$

Answer 1

The correct option is C $\text{temperature difference across}AB\text{is less than that of across}CD$

Temperature difference $\propto$ thermal resistance $\left(R\right)$
Where $R=\frac{l}{KA}$ or $R\propto \frac{1}{A}$
Area across $CD$ is less. Therefore, temperature difference across $CD$ will be more.