Two ends of a conducting rod of varying cross-section are maintained at `200^(@)C` and `0^(@)C` respectively. In steady state:

Options

A. temperature differences across `AB and CD` are equal
B. temperature difference aross `AB` is greater than that across `CD`
C. temperature difference aross `AB` is less than that across `CD`
D. temperature difference may be equal or different depending upon thermal conductivity of the rod.

Answer

C

Explanation

Rate of flow of heat `(dQ)/(dt)` of `H` is equal throughout the rod,
temperature difference is given by
`T.D = (H)` (thermal Resistance)
or `T.D prop` theramal Resistance `R`
Where `R = (l)/(KA) or R prop l/A`
Area across `CD` is less. therefore `T.D` across `CD` will be more`.