Which of the following cylindrical rods will conduct most heat, when their ends are maintained at the same steady temperature
ALength $1 m$ ; radius $1 cm$
BLength $2 m$ ; radius $1 cm$
CLength $2 m$ ; radius $2 cm$
DLength $1 m$ ; radius $2 cm$
Medium
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DLength $1 m$ ; radius $2 cm$
d (d)$\frac{Q}{t} = \frac{{KA\,\Delta \theta }}{l}$==> $\frac{Q}{t} \propto \frac{A}{l} \propto \frac{{{r^2}}}{l}$
$\frac{{{r^2}}}{l}$ is maximum in option $(d)$ , hence it will conduct more heat.
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