# GATE2016-2-15

A hollow cylinder has length $L$, inner radius $r_1$, outer radius $r_2$, and thermal conductivity $k$. The thermal resistance of the cylinder for radial conduction is

1. $\dfrac{\ln(r_2/r_1)}{2\pi kL} \\$
2. $\dfrac{\ln(r_1/r_2)}{2\pi kL} \\$
3. $\dfrac{2\pi kL}{\ln(r_2/r_1)} \\$
4. $\dfrac{2\pi kL}{\ln(r_1/r_2)}$

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