Two rods of lengths $l_{1}$ and $l_{2}$ are made of materials whose coefficients of linear expansion

Question

Two rods of lengths $l_{1}$ and $l_{2}$ are made of materials whose coefficients of linear expansion are $\alpha_{1}$ and $\alpha_{2}$. If the difference between two lengths is independent of temperature, then\

Professor PC Thomas Classes · Answer

For the difference in length to be independent of temp. increase in length of $\mathrm{I}^{	ext {st }}$ rod $=$ increase in length of $2^{	ext {nd }}$ rod\ $l_{1} \alpha_{1} \Delta 	heta=l_{2} \alpha_{2} \Delta 	heta$\