Two rods `A` and `B` are of equal lengths. Their ends of kept between the same temperature and their area of cross-section are `A_(1)` and `A_(2)` and thermal conductivities `K_(1)` and `K_(2)`. The rate of heat transmission in the two rods will be equal, if

Options

A. `K_(1)A_(2) = K_(2)A_(1)`
B. `K_(1)A_(1) = K_(2)A_(2)`
C. `K_(1)A_(1)^(2) = K_(2)A_(2)^(2)`
D. `K_(1)^(2)A_(1)`

Answer

B

Explanation

`because H_(1) =H_(2)`
`therefore ((TD)/R)_(1) = ((TD)/R)_(2)` (where TD = temperature difference )
or `R_(1) = R_(2)`
`therefore 1/(K_(1)A_(1))= 1/(K_(2)A_(2)) or K_(1)A_(1) = K_(2)A_(2)`