Entropy, What is?

Welcome back MechanicalEI, A very essential part of second law of thermodynamics is the concept of entropy. This makes us wonder: What is entropy? To know more about what how the kelvin-plank's and Clausius statement's equivalence is achieved, check out the second part. Now, We will explore entropy in this third part of the series. We begin with the Carnot's Theorem. Carnots Theorem states that of all engines operating between a given constant temperature source and a given constant temperature sink, none has a higher efficiency than a reversible engine. Also, Clausius theorem states that the cyclic integral of DQ upon t for a reversible cycle operating between two equilibrium states I and F is equal to 0. This integral can be replaced as the sum of two integrals one for R1 and other for R2, which can be rearranged as: (pause for 2 seconds). Since R2 is a reversible path. Hence, first is independent of the reversible path containing i and f. that is there exists a property of a system whose value at final state minus it’s valued at initial state is equal to 1. This property is called entropy and is denoted by S. Hence, we learnt about what the carnot and clausius theorem is, then we went on to find out that entropy is a property of the system.

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