Physics · 2019
JEE Main · 12 January 2019, Shift 1 · Q9
A cylinder of radius R is surrounded by a cylindrical shell of inner radius R and outer radius 2 R. The thermal conductivity of the material of the…
A cylinder of radius $\displaystyle R$ is surrounded by a cylindrical shell of inner radius R and outer radius $\displaystyle 2$ R . The thermal conductivity of the material of the inner cylinder is $\displaystyle \mathrm{K}_1$ and that of the outer cylinder is $\displaystyle \mathrm{K}_2$. Assuming no loss of heat, the effective thermal conductivity of the system for heat flowing along the length of the cylinder is :
Official answer
(3)
$\displaystyle \frac{K_1+3 K_2}{4}$
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JEE Main 2019 Physics question, with the answer from NTA’s final answer key. Where our answers come from.