Thermodynamics State/ Thermodynamics Process/ Thermodynamics Cycle

Thermodynamic States/state Of A System
Since we have seen that we can define the thermodynamics state or state of a system only when the system is in thermodynamic equilibrium (thermodynamics equilibrium means that the system must be in thermal, mechanical and chemical equilibrium). We will look at thermodynamic equilibrium later. Let us now define the state of the system.
        Assume that the system is in thermodynamic equilibrium then the state of a system is defined as- "When the condition of the system is completely described at a specific time by the properties of the system such as temperature, pressure, volume, etc. , it is called the state of the system". And these properties (like-T, P, V) are called state variables.
         These properties may be extensive or intensive. Extensive properties are additives whereas intensive properties are not additives.
Examples- A human body is an open system and its states are described by parameters like pressure, temperature, etc. at a particular time.

Thermodynamic Process
As we know that a system itself does not undergo any change. Rather, the state of the system changes. Thus, whenever a system undergoes a change in its state, the line joining the series of intermediate states through which the system has passed is called a path. And when this path is fully specified then it is called "Thermodynamic Process". 
OR
"When a system changes its state from one equilibrium state to another, the path of successive states through which the system has passed is called thermodynamic process".
OR
States of a thermodynamic system can be changed by interacting with its surroundings through heat and work. When this change occurs in a system, it is said that the system is undergoing a "Process".
☛ When there is an interaction between the system and the surrounding, the state of the system changes from one equilibrium to another. And these changes in the state of the system can be fast or slow and large or small. 

Thermodynamic Cycle
Whenever the properties of the system become the same as their previous values, we can say that the system has returned to its previous state, the system has undergone a "Cyclic Process Or In Thermodynamic Cycle". 
"A thermodynamic cycle is a sequence of different processes that begins and ends at the same thermodynamic state".

Note that even if a system has returned to its original state and completed one cycle, but it is not necessarily that the surrounding's state may be the same as before, it may have changed.


Hope you have found this article helpful!!!
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