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Consider a cycle followed by an engine a...

Consider a cycle followed by an engine as shown in figure,
1 to 2 is isothermal
2 to 3 is adiabatic
3 to 1 is adiabatic
Such a process does not exist because

A

heat is completely converted to mechanical energy in such a process, which is not possible.

B

mechanical energy is completely converted to heat in this process, which is not possible.

C

curves representing two adiabatic processes don't intersect.

D

curves representing an adiabatic process and an isothermal process don't intersect.

Text Solution

Verified by Experts

The correct Answer is:
A, C
(A) The given process is cyclic which starts from 1 and ends up at 1 again.
So , dU=0
Now, from first law of thermodynamics ,
dQ=dU+dW
`therefore` dQ=0+dW
`therefore` dQ=dW
Hence, heat energy supply to system converts totally into mechanical work which is not possible by second law of thermodynamics verifies option (A).
(C) Here, two curves are intersecting when the gas expands adiabatically from 2 to 3. It is not possible to return to the same state without being heat supplied. Hence, the process 3 to 1 cannot be adiabatic.
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