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Two identical rectangular blocks can be arranged either in configuration I or configuration II as shown. One block has thermal conductivity k and the other 2k. The temperature difference across the ends along the x-axis is the same in both configurations. If it takes 9 s to transport a certain amount of heat from the hot end to the cold end in configuration I, the time to transport the same amount of heat in configuration II is:
- 2.0 s
- 3.0 s
- 4.5 s
- 6.0 s
Correct answer: 2.0 s
Solution
The series arrangement (config I) carries a smaller heat current than the parallel arrangement (config II); the heat current ratio H_II/H_I = 9/2, so the time drops from 9 s to 9*(2/9) = 2.0 s.
Related JEE Advanced Physics questions
- Match the temperature of a blackbody listed in Group-I to the corresponding statement in Group-II, and select the correct answer.
[Given: Wien’s constant = 2.9 × 10⁻³ m-K and hc/e = 1.24 × 10⁻⁶ V-m]
Group-I:
(P) 2000 K
(Q) 3000 K
(R) 5000 K
(S) 10000 K
Group-II:
(1) The peak wavelength of emitted radiation can cause photoelectron ejection from a metal with a work function of 4 eV.
(2) The peak wavelength of emitted radiation falls within the visible spectrum.
(3) The peak wavelength of emitted radiation produces the broadest central diffraction maximum in a single-slit setup.
(4) The energy radiated per unit area is one-sixteenth of that emitted by a blackbody at 6000 K.
(5) The peak wavelength of emitted radiation is suitable for imaging human bones.
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- A continuous-flow calorimeter is used in two separate experiments to find the specific heat of a liquid. In the first trial, supplying 60 W raises the liquid temperature by 10 K. In the second trial, the power is doubled to 120 W, but the same 10 K rise is maintained by tripling the flow rate. Assuming heat loss to surroundings is the same in both trials, what is the power lost to the surroundings?
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