Khan Academy: Chemistry: Carnot Efficiency 2: Reversing the Cycle

Learn how the Carnot engine is the most efficient engine in this video lecture. The lecture begins with describing a heat engine and the steps of Carnot cycle. The video also explores how the engine would need to be frictionless and quasi-static to be reversible. Understand how the reverse cycle would require work to be applied to the system as heat is taken away from the cold body and given to the warm body. Also learn how the process obeys the second law of thermodynamics. [14:01]