PHYSICS IN FOCUS.

The article focuses on the principles of thermodynamics, particularly thermal equilibrium, the zeroth law of thermodynamics, and various thermodynamic processes. It explains that two systems are in thermal equilibrium when there is no net heat flow between them, and introduces the zeroth law, which establishes the concept of temperature. The text further discusses the first law of thermodynamics, which relates heat transfer, work done, and changes in internal energy, along with specific thermodynamic processes such as isothermal, adiabatic, isobaric, and isochoric processes. Additionally, it covers the efficiency of heat engines, particularly the Carnot engine, and the implications of the second law of thermodynamics regarding irreversible processes. [Extracted from the article]