Three conducting rods $\mathrm{AB}, \mathrm{BC}$ and $\mathrm{BD}$ made of same material and same cross…
Three conducting rods $\mathrm{AB}, \mathrm{BC}$ and $\mathrm{BD}$ made of same material and same cross section are arranged as shown in the figure. Temperatures at the points A, D and C are maintained at $20^{\circ} \mathrm{C}, 90^{\circ} \mathrm{C}$ and $0^{\circ} \mathrm{C}$ respectively. The ratio of lengths of $\mathrm{BD}$ to $\mathrm{BC}$ when there is no heat flow in $A B$, is
