Question

Three rods of same material and having same cross-
section have been joined as shown.
Each rod is of same length with one end kept at a constant
temperature as marked. Temperature of junction of the
three rods will be
(a) 45°C (b)60°C
(c)30°C (d) 20°C​

Answer 1

Answer:

Temperature of junction of three rods will be 45 °C

Answer 2

Temperature at junction will be 60°

• Three rods of same material and having same cross-

section have been joined as shown.

• Each rod is of same length with one end kept at a constant

temperature as marked.

• Let the temperature of junction be Q.
• Since roads B and C are parallel to each other (because both having the same temperature difference).
• Hence given figure can be redrawn as follows

                         $\frac{Q}{t} = \frac{Q1-Q2}{R}$

                              $\frac{Q}{t}AB =\frac{Q}{t}BC$

                         $\frac{90-Q}{R/2}= \frac{Q-0}{R}$

                            $180-2Q=Q$

                  Therefore,         Q=60°