gen-explain-the-carnot-cycle-as-you-would-to-a-capable-student-i-ba18

Explain the Carnot cycle as you would to a capable student, in 3-4 sentences.

The Carnot cycle is an idealized thermodynamic process that represents the most efficient possible heat engine operating between two temperatures. It consists of four reversible steps: isothermal expansion (absorbing heat from a hot reservoir), adiabatic expansion (cooling without heat exchange), isothermal compression (rejecting heat to a cold reservoir), and adiabatic compression (warming back to the starting state). The key insight is that no real engine can be more efficient than a Carnot engine operating between the same two temperatures, with efficiency determined solely by the temperature ratio: η = 1 - T_cold/T_hot. This theoretical limit helps engineers understand the fundamental constraints on real-world engines and refrigerators.