All real engines are less efficient than the Carnot engine because
A) they do not operate through the Otto cycle.
B) they do not operate through a reversible cycle.
C) the working substance does not maintain a constant volume through the cycle.
D) the working substance does not maintain a constant pressure through the cycle.
E) the working substance does not maintain a constant temperature through the cycle.

Question

Quizplus · Accepted Answer

The Carnot engine is the most efficient engine possible because it operates through a reversible cycle, which means that it can be run backwards to produce work while also absorbing heat from the surroundings. No real engine operates through a completely reversible cycle, making them all less efficient than the Carnot engine.

All Real Engines Are Less Efficient Than the Carnot Engine