Second Law and Entropy
PHYS 220 · Module 3
This module introduces entropy and the second law as guides to the direction of natural processes. Students study reversible and irreversible change, entropy calculations, and the physical origin of the arrow of time.
Lessons in this module
Entropy and the second law
Entropy is a state function that quantifies energy dispersal and microscopic multiplicity. This lesson introduces entropy and the second law of thermodynamics.
Reversible and irreversible processes
Reversible processes are ideal limits; irreversible processes are real and produce entropy. This lesson compares both and explains quasistatic change, dissipation, and entropy production.
Entropy calculations
Entropy changes can be calculated for heating, phase changes, ideal gas processes, and reservoirs. This lesson builds practical methods for computing $\Delta S$.
The arrow of time
The second law gives time a direction in macroscopic physics. This lesson explores why many processes happen one way but not the reverse, despite time-symmetric microscopic laws.
Ask your AI physics guide
Ask anything about Thermodynamics and Statistical Mechanics — Second Law and Entropy, or choose a suggested question below.
AI responses are educational and may not be perfectly accurate. Press Enter to send, Shift+Enter for new line.