The coefficient of thermal conductivity of copper is 9 times that of steel. In the composite cylindrical bar shown in the figure, what will be the temperature at the junction of copper and steel?

Step-by-step solution

Temperature of interface = K ₁ ₁ l ₂+ K ₂ ₂ l ₁ ~K ₁ l ₂+ K ₂ l ₁ It is given that K _ Cu =9 ~K _ s . So, if K _ s = K ₁= K , then K _ Cu = K ₂=9 ~K = 9 ~K 100 6+ K 0 18 9 ~K 6+ K 18 = 5400 ~K 72 ~K =75^ C