Four identical metal rods AB, BC, CD and BD are connected as shown in the diagram. Then in steady state, temperature of junction B is

If R be the thermal resistance of each rod, then equivalent thermal resistance between A and D isRAD=R+(2R×R2R+R)=5R3∴ In steady state rate of heat conduction Q=100−50RAD=505R/3=30RFor the rod AB, Q=100−θR⇒θ=100−(30R)R=70oC