Thermodynamics

Heat Engines

1. A heat engine is a device that converts heat energy into mechanical work.
2. It operates between a hot reservoir and a cold reservoir.
3. The working principle is based on the First and Second Laws of Thermodynamics.
4. The efficiency of a heat engine is given by η = W/Q₁, where:
   • W is the work output.
   • Q₁ is the heat absorbed from the hot reservoir.

Entropy

1. Entropy is a measure of the disorder or randomness of a system.
2. The symbol for entropy is S, and its SI unit is joules per kelvin (J/K).
3. It quantifies the unavailability of a system's energy to perform useful work.
4. The Second Law of Thermodynamics states that entropy always increases in a spontaneous process.
5. ΔS = Q/T, where:
   • ΔS is the change in entropy.
   • Q is the heat exchanged.

Zeroth Law of Thermodynamics

1. The Zeroth Law of Thermodynamics defines the concept of thermal equilibrium.
2. If two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
3. This law provides the foundation for the definition of temperature.
4. Thermometers work based on the Zeroth Law.

First Law of Thermodynamics

1. The First Law of Thermodynamics is a statement of the conservat