When a system undergoes a change of state, a process occurs. The succession of states passed through during a change of state is called path. The path is completely specified in a process. For example, a constant volume process, a constant temperature process etc.
1.8.2 Mechanical Equilibrium
A thermodynamic cycle is defined as a number of processes in sequence where the final state is identical to its initial state.
Fig. 1.6 shows A – B as a process and 1-2-1 as a cycle. To complete a cycle, there may be number of processes in between. When the system comes to its original state after passing through a sequence of processes, then it is called a cyclic process. 1-2-1 is a cyclic process.