Characteristics and examples of Irreversible process
The process which cannot be retracted in opposite direction by reversing is called irreversible process. It is also called indelible process. For instance, heat flow between two bodies occurs due to the temperature gradient between the two bodies; this is, in fact, the natural flow of heat. Similarly, water flows from high level to low level, current moves from high potential to low potential, etc.
The irreversible process occurs suddenly and spontaneously. In nature, all the processes occur spontaneously. So, natural phenomena are irreversible. In this process, the system never shows the tendency to go back to its initial state. It is a very rapid process and thermodynamic equilibrium is not maintained.
Examples: Some of the examples of the irreversible process are given below.
(i) When current flows through an electric resistor heat is produced. It is an irreversible process.
(ii) Heat produced due to the function of two bodies is an irreversible process. This is because that work done against friction is transformed into heat and that heat can never be transformed into work.
(iii) When two bodies having different temperatures are in contact with each other, heat will flow from the body of higher temperature to the body of lower temperature. But no tendency will be found for the flow of heat from the body of lower temperature to the body of higher temperature. So it is an irreversible process.
(iv) When a bullet is fired from a gun, an explosion of gunpowder takes places. This explosion takes place very quickly. This process is an irreversible process.