Three rods $AB, BC$ and $AC$ having thermal resistances of $10\, units, \,10 \,units$ and $20 \,units,$ respectively, are connected as shown in the figure. Ends $A$ and $C$ are maintained at constant temperatures of $100^o C$ and $0^o C,$ respectively. The rate at which the heat is crossing junction $B$ is   ........ $ \mathrm{units}$

814-18

  • A

    $5$

  • B

    $10$

  • C

    $20$

  • D

    $7.5$

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