Q.

Rods x and y of equal dimensions but of different materials are joined as shown in the figure. Temperatures of end points A and F are maintained at 100°C and 40°C respectively. Given the thermal conductivity of rod x is three times of that of rod y, the temperature at junction points B and E are (close to):         [2026]

1 89 °C and 73 °C respectively  
2 80 °C and 60 °C respectively  
3 80 °C and 70 °C respectively  
4 60 °C and 45 °C respectively  

Ans.

(1)

Let [R=3KA]

H=[100-4011R2]    ...(1)

H=100-TBR    ...(2)

H=TE-403R    ...(3)

Using (1) and (2)

120=1100-11TA

TB=89°C

Using (1) and (3)

TE=73°C