Second law of thermodynamics

Second law of thermodynamics

Ø    The second law of thermodynamics states that the entropy of an isolated system never decreases.

Ø   It retains the energy conservation between mechanical work and heat. But it does not state the condition of conversion as well as direction of heat transferred.

The statement of this law can be given in number of ways.

1.Clausius statement

Ø    Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.

2.Kelvin statement

Ø    It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects.

3.Planck's proposition

 

Ø    It is impossible to construct an engine which will work in a complete cycle, and produce no effect except the raising of a weight and cooling of a heat reservoir.

 

4.Planck's statement 

Ø    Every process occurring in nature proceeds in the sense in which the sum of the entropies of all bodies taking part in the process is increased. In the limit, i.e. for reversible processes, the sum of the entropies remains unchanged.