Three conducting rods of same material and cross section are shown in figure. Temperature at $A,D$ and $C$ are maintained at $20\ ^oC, 90\ ^oC$ and $0\ ^oC$. The ratio of lengths of $BD$ and $BC$ if there is no heat. Flows in $AB$ is
  • A$\frac{2}{7}$
  • B$3.5$
  • C$4.5$
  • D$\frac{2}{9}$
Medium
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