Physics 312 Lecture: "The Carnot Cycle and Second Law of Thermodynamics" May 11, 1998

another way to state the Second Law of Thermodynamics is
"heat does not spontaneously flow from cold to hot objects."
a reversible process is one which can be performed in reverse so that the system is restored to its original condition
it is NOT possible to reverse processes with friction or turbulence
Carnot's Theorem state
"no heat engine operating between two heat reservoirs can be more efficient than a reversible one."
a corollary to Carnot's Theorem is that
"all reversible engines operating between the same heat reservoirs have the same efficiency."
one example of a reversible set of operations is the Carnot cycle, which goes
- isothermal expansion (add heat)
- adiabatic expansion
- isothermal contraction (eject waste heat)
- adiabatic contraction
the efficiency of the Carnot cycle (or any reversible cycle) depends only on the temperatures of the hot and cold reservoirs:
```
              e = 1 - Tc/Th
```
the Third Law of Thermodynamics states that
"it is impossible to lower the temperature of any substance to zero Kelvin in a finite number of steps;"
this makes it impossible to reach 100 percent efficiency

This lecture discusses material in Chapter 22 of Serway.