A wall consists of alternating blocks withlength 'd' and coefficient of thermal conductivity `k_(1)` and `k_(2)`. The cross sectional area of the blocks are the same. The equivalent coefficient of thermal conductivity of the wall between left and right is:-

Options

A. `K_(1)+K_(2)`
B. `((K_(1)+K_(2)))/(2)`
C. `(K_(1)K_(2))/(K_(1)+K_(2))`
D. `(2K_(1)+K_(2))/(K_(1)+K_(2))`

Answer

B