A wall has two layers A and B, each made of different material. Both the layers have the same thickness. The thermal conductivity of the material of A is twice that of B . Under thermal equilibrium, the temperature difference across the wall is `36^@C.` The temperature difference across the layer A is

Options

A. `6^(@)C`
B. `12^(@)C`
C. `18^(@)C`
D. `24^(@)C`

Answer

B

Explanation

Given that temperature difference across the wall is `36^(@)C` Let temperature difference across `A` is `Deltatheta` then temperature difference across `B` is `36 -Deltatheta`
In steady state, `(2KADeltatheta)/(x)=(KA(36-Deltatheta))/(x)`
.