**Cyclic and
Non – Cyclic Process**

A cyclic process consists of a series of changes which return the system back to its initial state. In non – cyclic process the series of changes involved do not return the system back to its initial state.

(1) In case of cyclic process as \({{U}_{f}}={{U}_{i}}\Rightarrow \Delta U={{U}_{f}}-{{U}_{i}}=0\) i.e. change in internal energy for cyclic process is zero and also \(\Delta U\propto \Delta T\Rightarrow \Delta T=0\) i.e. temperature of system remains constant.

(2) We know that \(\Delta Q=\Delta U+\Delta W\Rightarrow \Delta Q=\Delta W\) i.e. heat supplied is equal to the work done by the system.

(3) For cyclic process P – V graph is a closed curve and is enclosed by the closed path represents the work done.

If the cycle is clockwise work done is positive and if the cycle is anticlockwise work done is negative.

(4) Work done in non – cyclic process depends upon the path chosen or the series of changes involved and can be calculated by the area covered between the curve and volume axis on PV diagram.