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.
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