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Cyclic Process
Concepts tested here
- Internal energy is a state function
All Questions
2008 AIPMT 1 question
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If $Q$, $E$ and $W$ denote respectively the heat added, change in internal energy and the work done in a closed cycle process, then :In a cyclic process the system returns to its initial state, so the initial and final states are the same.
Internal energy is a state function; it depends only on the state of the system.
Therefore the initial and final internal energies are equal and the change in internal energy is zero: $E = 0$.
From the first law, $Q = E + W$, so for a cycle $Q = W$.
$Q$ and $W$ are not zero in general (the work equals the area enclosed by the cycle on the P-V diagram); they are only equal to each other.
Hence the correct relation is $E = 0$.