Question

Three rods of a same material same area of cross-section but different lengths 10 cm, 20 cm, and 30 cm are connected at a point as shown. What is a temperature of junction O?

• A. 19.2
• B. 16.4
• C. 11.5
• D. 22

Answer 1

The correct option is A 19.2

Let the temperature at point 0 be $T_0$

so,

$\frac{T_A-T_O}{l_1}=\frac{T_O-T_B}{l_2}+\frac{T_O-T_C}{l_3}$

$\frac{30-T_O}{30}=\frac{T_O-10}{10}+\frac{T_O-20}{20}$

Solving this

$T_O=19.2$