Sample 1Medium
Two rods of equal length and equal cross-section are joined end to end and lagged along their sides. Rod 1 has thermal conductivity K and its free end is held at 100 °C; rod 2 has conductivity 2K and its free end is held at 0 °C. In the steady state, what is the temperature of the junction?
Show the answer
The answer is C.
In the steady state the heat current is the same in both rods: K(100 − T) = 2K(T − 0), so T = 100/3 ≈ 33.3 °C.
- A.
50 °C holds only if the two conductivities are equal.
- B.
66.7 °C would result if the better conductor were at the hot end.
- D.
25 °C does not satisfy K(100 − T) = 2K T.
NCERT: Class 11 Physics, Chapter 10