Three rods of identical cross-section and length are made of three different materials of thermal conductivity K 1 , K 2 and K 3 , respectively. They are joined together at their ends to make a long r

Question

Three rods of identical cross-section and length are made of three different materials of thermal conductivity $K_{1}, K_{2}$ and $K_{3}$ , respectively. They are joined together at their ends to make a long rod (see figure). One end of the long rod is maintained at $100 ° C$ and the other at $0 ° C$ (see figure). If the joints of the rod are at $70 ° C$ and $20 ° C$ in steady and there is no loss of energy from the surface of the rod, the correct relationship between $K_{1}, K_{2}$ and $K_{3}$ is :

Question diagram: Three rods of identical cross-section and length are made of

Options:

Answer:

A

Solution:

$K_{1} (100 - 70) = K_{2} (70 - 20) = K_{3} (20 - 0)$

$K_{1} 30 = K_{2} (50) = K_{3} (20)$

$\Rightarrow K_{1} : K_{2} : K_{3} = 10 : 6 : 15$

$K_{1} : K_{3} = 2 : 3$

TestHub · Accepted Answer

K 1 ( 100 - 70 ) = K 2 ( 70 - 20 ) = K 3 ( 20 - 0 ) K 1 30 = K 2 ( 50 ) = K 3 ( 20 ) ⇒ K 1 : K 2 : K 3 = 10 : 6 : 15 K 1 : K 3 = 2 : 3

Physics - Heat & Thermo Question with Solution | TestHub

Options:

Doubts & Discussion