Laws of thermodynamics
Zeroth law of thermodynamics
When a body A is in
thermal equilibrium with a body B and with a body C separately then B and C
will also be in thermal equilibrium with each other. This is called Zeroth law
of thermodynamics. It is the basis of temperature measurement.
First law of thermodynamics
First law of
thermodynamics is also known as the law of conservation of energy. It states
that “Energy can neither be created nor be destroyed, it can only be
transformed from one form to another.”
Perpetual motion machine of first kind or PMM-1
By the first law of
thermodynamics, it is impossible to create a machine which would continuously
supply mechanical work without consuming any other form of energy. Such a
fictitious machine is Perpetual motion machine of first kind or PMM-1. Thus,
PMM-1 is impossible.
Second law of thermodynamics
First law of
thermodynamics talks only about energy and its accountability but it does
provide any clue about the spontaneity, probability and direction of process.
Second law of
thermodynamics, also called as directional law, says that
1.
Heat always
flow from a body at higher temperature to a body at lower temperature.
2.
The reverse
of these process never happen spontaneously.
Kelvin-Plank statement of second law of thermodynamics
It states that “it is impossible
for a heat engine to produce net-work in a complete cycle if it exchanges heat
only with bodies at a single fixed temperature.”
Perpetual Motion Machine of second kind or PMM-2
PMM-2 is a machine
which violates the Kelvin-Planck statement of second law i.e. PMM-2 is a
machine which produces work while exchanging heat with bodies at a single fixed
temperature or in other words it converts complete heat energy into work and
does not reject any heat i.e. its efficiency is 100%. Such a machine is
impossible and it is called Perpetual Motion Machine of second kind (PMM-2).
Clausius’ statement of second law
It is impossible to construct a device which, operating
in a cycle, will produce no effect other than the transfer of heat from a
cooler body to a hotter body.
