Four rods of same material with different radii r and length λ are used to connect two reservoirs of heat at different temperatures. Which one will conduct most heat ?
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Four rods of same material with different radii r and length λ are used to connect two reservoirs of heat at different temperatures. Which one will conduct most heat ?

G1 Physics · Accepted Answer

Use the first law Q=ΔU+W (W by the gas), ΔU=nCᵥΔT for an ideal gas, and the appropriate process relation. For Carnot devices, let T₁ be the cold-reservoir temperature and T₂ be the hot-reservoir temperature; η=1−T₁/T₂ and COP=T₁/(T₂−T₁). Evaluating the given data/statements gives r = 2cm, λ = 0.5m. Therefore the correct answer is A.