JEE Advanced2013PhysicsThermal Properties of MatterActual
Two rectangular blocks, having identical dimensions, can be arranged either in configuration I or in configuration I I as shown in the figure. One of the blocks has thermal conductivity K and the other 2 K . The temperature difference between the ends along the x-axis is the same in both the configurations. It takes 9 s to transport a certain amount of heat from the hot end to cold end in the configuration I . The ti
Options
- A2.0 s
- B3.0 s
- C4.5 s
- D6.0 s
Correct answer
A. 2.0 s
Step-by-step solution
In the first combination, the 2 blocks are having thermal conductivity 2 K and 2 K respectively are in series combination. Therefore the Keq will be 1 K     + 1 2 K and the Keq in case of parallel combination is 3K Heat transferred = Rate × time. ​ ∴    Rate 1 × time 1 = Rate 2 × time 2 . Δ T × 9 L KA + L 2 KA = Δ T × t L 3KA ⇒   t = 2