Question

Five identical rods are joined as shown in figure. Point A and C are maintained at temperature ${120}^{\circ }$ C and ${20}^{\circ }$ C respectively. The temperature of junction B will be

• A. ${100}^{\circ }$ C
• B. ${80}^{\circ }$ C
• C. ${70}^{\circ }$ C
• D. $0^{\circ }$ C

Answer 1

The correct option is C ${70}^{\circ }$ C

If thermal resistance of each rod is considered R then, the given combination can be redrawn as follows

$(Thermalcurrent{)}_{AC}=(Thermalcurrent{)}_{AB}$
$\frac{(120-20)}{R}=\frac{(120-\theta )}{R}\Rightarrow \theta ={70}^{\circ }C$.