Three rods of Copper Branss and Steel are welded together to form a Y-shaped structure Area of cross -section of each rod is `4cm^(-2)` End of copper rod is maintained at `100^(@)C`, where as ends of brass, steel are kept at `0^(@)C` Lenths of the copper brass and steel rods are `46,13` andd `12cms` respectively The rods are thermally insulated from surroundings except at ends Thermal conductivities of copper, brass and steel are `0.92,0.26` and `0.12 CGS` units respectively Rate of heat flow through coper rod is .

Explanation

Let `theta` junction temperature Given `A =4cm^(2)`
`l_(cu) = 46cm,l_(Br) = 13cm, &l_(steel) = 12cm`
`K_(cu) =0.92, K_(Br) = 0.26 &K_(steel) = 0.12C.G.S.units`
In steady state `((Q)/(t))_(cu)=((Q)/(t))_(branss)+((Q)/(t))_(steel)`
`(K_(Cu)A(100-theta))/(l_("cul"))=(K_(Br)A(theta-0))/(l_(Br))+(K_(steel)A(theta-0))/(l_(steel))`
`(0.92A(100-theta))/(46) = (0.26A(theta-0))/(13) +(0.12A(theta-0))/(12)`
`rArr theta = 40^(@)C`
`:.((Q)/(t))_(cu)=(K_(cu)A(100-theta))/(l_(Cu)) = 4.8cal//sec`
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