A reversible process is one which can be retraced in exactly the same order, without producing any change in the surroundings. In the reversible process, the working substances pass through the same stages as in the direct process but thermal and mechanical effects at each stage are exactly reversed. If heat is absorbed in the direct process it will be given out in the reverse process and if work is done by the substance in the direct process than the work will be done on the substance on the reverse process.
Hence the working substance is restored to its original conditions. Although no actual change is completely reversible but the process of liquefaction and evaporation of a substance performed slowly are practically reversible. Similarly the slow compression of a gas in a cylinder is reversible process as the compression can be changed to expansion by slowly decreasing the pressure on the piston to reverse the operation.
If a process can not be retraced in the backward direction by reversing the controlling factors, it is an irreversible process. All changes which occur suddenly or which involve friction or dissipation of energy through conduction, convection or radiation are irreversible. An example of highly reversible process is an explosion.
Hence the working substance is restored to its original conditions. Although no actual change is completely reversible but the process of liquefaction and evaporation of a substance performed slowly are practically reversible. Similarly the slow compression of a gas in a cylinder is reversible process as the compression can be changed to expansion by slowly decreasing the pressure on the piston to reverse the operation.
If a process can not be retraced in the backward direction by reversing the controlling factors, it is an irreversible process. All changes which occur suddenly or which involve friction or dissipation of energy through conduction, convection or radiation are irreversible. An example of highly reversible process is an explosion.
