Question

Six identical conducting rods are joined as shown in the figure. Points $A$ and $D$ are maintained at $200 \, ^\circ C$ and $20 \, ^\circ C$ respectively. The temperature of junction $B$ will be -

• A. $120^\circ C$
• B. $100^\circ C$
• C. $140^\circ C$
• D. $80^\circ C$

Answer 1

Answer: (C)

Electrical circuit,



$\left(\frac{d q}{d t}\right)_{1}=\left(\frac{d Q}{d t}\right)_{2}$
$\frac{k a \left(\right. 200 - \theta \left.\right)}{l}=\frac{k A \left(\right. \theta - 20 \left.\right)}{2 l}$
$400-2\theta =\theta -20 \, ;$
$\theta =\frac{420}{3}=140^\circ C$