Question

Two rectangular blocks, having identical dimensions, an be arranged either in configuration-I or in configuration-II as shown in the figure. One of the blocks has thermal conductivity k and the other 2k. The temperature difference between the ends along the x-axis is the same in both the configurations. It takes 9s to transport a certain amount of heat from the hot end to the cold end in the configuration-I. The time to transport the same amount of heat in the configuration-II is

A. `2.0s`
B. `3.0s`
C. `4.5s`
D. `6.0s`

Answer 1

`DeltaT=(Q)/(t_(2))(2r)/(3)`………`(2)`
`implies (t_(1))/(t_(2))=(3r)/(2r)xx3`
`t_(2)=(2)/(9)xx9=2s`