Thermal Properties of Matter

JEE Main level, single correct, medium

97 of 126

Question 97 of 126

Two metallic blocks M1{M}_{1} and M2{M}_{2} of same area of cross-section are connected to each other (as shown in figure). If the thermal conductivity of M2{M}_{2} is KK then the thermal conductivity of M1{M}_{1} will be : [Assume steady state heat conduction]

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Answer: (B) 8K8K

Let thermal conductivity of M1{M}_{1} be K′K'.
Using heat current relation for steady state conduction,
K′A(100−80)16=KA(80−0)8\dfrac{K'A\left(100-80\right)}{16}=\dfrac{KA\left(80-0\right)}{8}
⇒K′×2016=K×808⇒K′=8K\Rightarrow \dfrac{K'\times 20}{16}=\dfrac{K\times 80}{8} \Rightarrow K'=8K

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