A Carnot engine runs between a hot reservoir at T_h and a cold reservoir at T_c.If one of the temperatures is either increased or decreased by 3.5 K,which of the following changes would increase the efficiency by the greatest amount? A)increasing T_h B)increasing T_c C)decreasing T_c D)cannot be determined from information given

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Quizplus · Accepted Answer

The efficiency of a Carnot engine is given by E = 1 - Tc/Th, where Tc and Th are the temperatures of the cold and hot reservoirs, respectively. To maximize the efficiency, we want to maximize (Th - Tc) while keeping Th and Tc as different as possible. If we increase Th, the temperature difference Th - Tc would decrease, which would decrease the efficiency. Similarly, if we increase Tc, the temperature difference would decrease, which would also decrease the efficiency. However, if we decrease Tc by 3.5 K, the temperature difference Th - Tc would increase by 3.5 K, which would increase the efficiency. Therefore, the best choice is C: decreasing T_c.

A Carnot Engine Runs Between a Hot Reservoir at Th

A Carnot Engine Runs Between a Hot Reservoir at T_h