Entropy - Physical Meaning

In summary, entropy is a measure of the increase of internal energy with temperature and its units are Joules per Kelvin."
  • #1
TimNguyen
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Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?
 
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  • #2
TimNguyen said:
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?

The most simple and direct interpretation

[tex]U = TS[/tex]

entropy is a "measure" of the increase of internal energy with temperature or

[tex]S = \frac{U}{T}[/tex]

If two bodies have the same temperature but one has more energy, then it has more entropy.

If two bodies have the same energy but one has less temperature, then it has more entropy.
 
Last edited:
  • #3
TimNguyen said:
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?

Try this:

http://www.entropysite.com/

It has a good collection of basic articles, especially in dispelling the notion that entropy is nothing more than "disorder".

Zz.
 
  • #4
ZapperZ said:
Try this:

http://www.entropysite.com/

It has a good collection of basic articles, especially in dispelling the notion that entropy is nothing more than "disorder".

Zz.

Nice link!

Effectively, the old (archaic) idea of entropy like disorder is not justified and would be abandoned of literature.

Moreover, the standard formula [tex]S = k \ ln W[/tex] often invoked in that old interpretation is valid only in the very special case of an isolated system at equilibrium.

That is reason that one would reasoning what is entropy from above formulas.
 
  • #5
TimNguyen said:
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?
ans:
it really means how quickly the energy is spreding in medium.
 
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What is entropy?

Entropy is a scientific concept that refers to the measure of the disorder or randomness in a system. It is often described as the level of uncertainty or unpredictability in a system.

What is the physical meaning of entropy?

The physical meaning of entropy is that it represents the amount of energy that is not available to do work in a system. As a system becomes more disordered, the amount of energy available to do work decreases, resulting in an increase in entropy.

How is entropy related to the second law of thermodynamics?

The second law of thermodynamics states that the total entropy of a closed system will always increase over time. This means that as a system evolves, it will become more disordered and less organized, leading to an increase in entropy.

What are some everyday examples of entropy?

Some everyday examples of entropy include a melting ice cube, a broken egg, and a disorganized room. In each of these examples, the system starts off in a more organized state and then becomes more disordered over time, resulting in an increase in entropy.

How is entropy used in different fields of science?

Entropy is a fundamental concept in many fields of science, including physics, chemistry, biology, and information theory. It is used to understand and predict the behavior of complex systems, such as chemical reactions, biological processes, and even the universe as a whole.

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