Question

Six identical conducting rods are joined as shown in figure. Points A and D are maintained at temperatures 200^0C and 20^0C respectively. The temperature of junction B will be

• A. 120^0C
• B. 100^0C
• C. 140^0C
• D. 80^0C

Answer 1

Answer: (C)

140^0C

Answer 2

Let the thermal resistance of each rod is R

Effective thermal resistance between B and D = 2R

Temperature of interface $\theta = \frac{R_{1}\theta_{2} + R_{2}\theta_{1}}{R_{1} + R_{2}}$

$\theta = \frac{R \times 20 + 2R \times 200}{R + 2R} = \frac{420}{3} = 140^{o}C.$