The heat is flowing through two cylindrical rods of same material. The diameters of the rods are in the ratio $1 : 2$ and their lengths are in the ratio $2 : 1$ . If the temperature difference between their ends is the same, the ratio of rate of flow of heat through them will be
A$1:1$
B$2:1$
C$1:4$
D$1:8$
AIPMT 1995, Medium
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D$1:8$
d (d) $\frac{Q}{t} = \frac{{KA\,\Delta \theta }}{l}$
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