Q: Give Kelvin‐Planck and Clausius statements of the second law of thermodynamics.
Justify that violation of the Kelvin‐Planck statement leads to violation of the Clausius statement and vice versa.
Kelvin‐Planck statement: It is impossible to construct a heat engine or device which operates in a cycle that produces no other effects than the production of work and the transfer of heat from a single body.
The efficiency of such an engine would be 100 %
Such a device violates Kelvin-Planck’s statement even though it satisfies the first law of thermodynamics, i.e. principle of conservation of energy.
Fig. A heat engine that violates the Kelvin‐Planck statement of the second law cannot be built
Fig. A heat engine that favors the Kelvin‐Planck statement
“It is impossible to construct a device that operates on a cycle whose main result is the transfer of heat from a cooler body to a hotter body without the assistance of external work.
According to the above statement, it is clear that heat cannot flow itself from a lower temperature body to a higher temperature body without the assistance of an external work [Figure (a)]. This process is impossible and violates the Clausius statement of the second law of thermodynamics.
Alternatively, heat can transfer from a low-temperature body to a high-temperature body with the help of external work (W) [Figure (b)]. This process is possible.