Which statement correctly describes thermal equilibrium?

Thermal equilibrium occurs when two systems in thermal contact no longer exchange heat energy because they have reached the same temperature. This means that there is no net heat flow between the systems, leading to a balance in thermal energy. When thermal equilibrium is achieved, all parts of the system have uniform temperature, and any thermal interactions that may have existed are effectively neutralized.

The concept of thermal equilibrium is fundamental in thermodynamics as it provides a basis for understanding heat transfer. This situation can occur in closed systems, isolated systems, and also in open systems as long as there is no heat flow due to a temperature difference. Other statements that suggest varying temperatures, complete loss of heat, or restrictions to open systems do not accurately reflect the definition of thermal equilibrium.