Three rods A B, B C and B D made of the same material and having the same cross-section have been joined as shown in the figure. The ends A, C and D are held at temperatures of 20^ C , 80^ C and 80^ C respectively. If each rod is of same length, then the temperature at the junction B of the three rods is

Step-by-step solution

Let the temperature of function . Since, rod B C and B D are parallel to each other (because both having the same temperature difference). Hence, given figure can be redrawn as follows ( R be the resistance of each rod). Q t = ( ₁- ₂ ) R and ( Q t )_ A B = ( Q t )_ B D (80- ) R / 2 = ( -20^ ) R =60^