Question

Six identical conducting rods are joined as shown in figure. Points A and D are maintained at temperatures 200${}^{\circ }$C and 20 ${}^{\circ }$ C respectively. Find the temperature of junction B.

• A. 120 deg C
• B. 140 deg C
• C. 160 deg C
• D. 180 deg C

Answer 1

The correct option is B

140 deg C

Let the thermal resistance of each rod is R

Effective thermal resistance between B and D = 2R

Temperature of interface $\theta =\frac{R_1{\theta }_2+R_2{\theta }_1}{R_1+R_2}$

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