Two rods one of length L and the other of length 2L are made of the same material and have the same diameter. The two ends of the longer rod are maintained at 100°C. One end of the shorter rod is maintained at 100°C while the other end is insulated. Both the rods are exposed to the same environment at 40°C. The temperature at the insulated end of the shorter rod is measured to be 55°C. The temperature at the midpoint of the longer rod would be
- A. 40°C
- B. 50°C
- C. 55°C
- D. 100°C
Answer: C. 55°C
Explanation: By symmetry, the midpoint of the 2L rod with both ends at 100°C is equivalent to the insulated end of a length L rod with one end at 100°C (adiabatic boundary condition at symmetry plane).