A Carnot engine E is working between two temperatures 473 K and 273 K. In a new system, two engines are used: engine E₁ works between 473 K and 373 K, and engine E₂ works between 373 K and 273 K. If η₁₂, η₁ and η₂ are the efficiencies of the engines E, E₁ and E₂ respectively, then

Question

Accepted Answer

(1) η₁₂<η₁+η₂. η₁₂=1-(273)/(473)=0.423. η₁=1-(373)/(473)=0.211 and η₂=1-(273)/(373)=0.268. η₁+η₂=0.479>0.423. The two efficiencies do not simply add because E₂ works on the heat E₁ rejects, not on the original input.

A Carnot engine E is working between two temperatures 473 K and 273 K. In a new system, two engines are used: engine E₁ works between 473 K and 373 K, and engine E₂ works between 373 K and 273 K. If η₁₂, η₁ and η₂ are the efficiencies of the engines E, E₁ and E₂ respectively, then

Step-by-step solution

Why the other options are wrong