Thermodynamics - Thermodynamic Processes

A Quasi-static process is an idealized process that occurs so slowly that the system remains in thermal and mechanical equilibrium with its surroundings at every instant.

An Isothermal Process is a thermodynamic process in which the temperature of the system remains constant ($T = \text{constant}$). For an ideal gas, the change in internal energy is zero ($\Delta U = 0$), and the process follows Boyle's Law: $PV = \text{constant}$.

An Adiabatic Process is one in which there is no exchange of heat between the system and the surroundings ($\Delta Q = 0$). This usually happens when the system is thermally insulated or the process is very fast. It follows the relation $PV^\gamma = \text{constant}$.

An Isobaric Process occurs at constant pressure ($P = \text{constant}$). The work done is $W = P(V_2 - V_1)$ and the heat supplied is used to change both internal energy and perform work.

An Isochoric Process occurs at constant volume ($V = \text{constant}$). Since there is no change in volume, the work done $W = 0$. By the first law, all heat supplied goes into increasing the internal energy: $\Delta Q = \Delta U$.

The First Law of Thermodynamics is a statement of conservation of energy: $\Delta Q = \Delta U + \Delta W$, where $\Delta Q$ is heat supplied, $\Delta U$ is change in internal energy, and $\Delta W$ is work done by the system.