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Ben-Gurion University of the Negev
Department of Physics
Thermodynamics & Statistical Mechanics 1
‫גוריון בנגב‬-‫אוניברסיטת בן‬
‫המחלקה לפיסיקה‬
1 ‫תרמודינמיקה ומכניקה סטטיסטית‬
Tutorial 12 – Heat and Work 1
1.
Magnetic engine
Consider a system of N magnetic dipoles in an external magnetic field B and in temperature
T. Each dipole has two states in the direction of the magnetic field: m, -m.
a. Find the partition function, the average magnetization, the average energy, and the
entropy
b. Consider an isothermal process where the magnetic field is changed from B1 to B2.
What is the work done on the system and what is the amount of heat absorbed by
it?
c. Consider an adiabatic process where the magnetic field is changed from B2 to B3.
What is the work done on the system?
d. Sketch the engine cycle and calculate its efficiency