Question

Three rods made of the same material and having the same cross section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at 0°C and 90°C respectively. The temperature of the junction of the three rods will be

(a) 45°C 

(b) 60°C 

(c) 30°C 

(d) 20°C

Answer 1

Correct Answer is: (b) 60°C 

As the rods are made of the same material and have the same dimensions, they have the same thermal resistance, say R. Let θ be the temperature of the junction.

The circuit becomes as shown in the figure below.

or 180°C - 2θ = θ or θ = 60°C.