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Carnot cycle
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Two isothermal and two adiabatic steps.
carnotTwo isothermal and two adiabatic reversible steps: isothermal expansion at T_h, adiabatic expansion, isothermal compression at T_c, adiabatic compression.
Explore it in the Carnot lab.
Reversible processes are idealisations.
In more detail
The Carnot cycle consists of two isothermal and two adiabatic processes. Its reversibility makes it the reference for maximum efficiency.
Real-world uses
- Physics courses use the Carnot cycle to derive efficiency limits.
- It serves as a benchmark for comparing real engine cycles.
- The Carnot cycle is used in textbooks to show the maximum efficiency possible for an engine between two reservoirs.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
What are the four steps?
Isothermal expansion, adiabatic expansion, isothermal compression and adiabatic compression.
Can a real engine follow it exactly?
No. Real engines have friction and finite heat transfer rates.
What are the four steps of the Carnot cycle?
Two isothermal steps, where heat is absorbed and rejected, and two adiabatic steps, where the temperature changes with no heat exchange.
Related topics in Heat & Thermodynamics
Clausius statement · Heat engines · Carnot engine · Refrigerators and heat pumps · Otto cycle · Diesel cycle