What principle describes the efficiency of heat engines developed by Carnot?

The principle that describes the efficiency of heat engines developed by Carnot is known as the Carnot theorem. This theorem establishes the maximum possible efficiency that any heat engine can achieve when operating between two thermal reservoirs. The efficiency is determined by the temperatures of the hot and cold reservoirs, and it states that no engine operating between these two temperatures can be more efficient than a Carnot engine, which is an idealized engine that operates on a reversible cycle.

Specifically, the Carnot theorem provides the formula for efficiency, which is given by the difference in temperatures between the two reservoirs, expressed as a fraction of the temperature of the hot reservoir. This fundamental principle highlights the importance of absolute temperatures (measured in Kelvin) when assessing the performance of heat engines, and it sets a theoretical limit on efficiency that aids in the design and analysis of real-world thermal machines.

Understanding this theorem is crucial for anyone studying thermodynamics, as it not only clarifies the relationship between heat transfer and work output in engines but also underscores the significance of operating conditions in maximizing energy conversion.