Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are K_1 and K_2 . The thermal conductivit - Physics MCQ NEET 2017 2026 | ExamTest.live

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Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are K_{1} and K_{2} . The thermal conductivity of the composite rod will be:

Solution & Step-by-step Explanation

The rods are connected in parallel as they are welded along their lengths and share the same temperature difference between their ends.Equivalent thermal resistance R_{e q} for parallel combination: \frac{1}{R _{e q}} = \frac{1}{R _{1}} + \frac{1}{R _{2}} \frac{K _{e q} ( 2 A )}{d} = \frac{K _{1} A}{d} + \frac{K _{2} A}{d} 2 K_{e q} = K_{1} + K_{2} ⟹ K_{e q} = \frac{K _{1} + K _{2}}{2} .

Try it yourself before checking the explanation above.

Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are K_{1} and K_{2} . The thermal conductivity of the composite rod will be:

\frac{K _{1} + K _{2}}{2}

\frac{3 ( K _{1} + K _{2} )}{2}

K_{1} + K_{2}

2 (K_{1} + K_{2})

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