Change of entropy in a resistor

AI Thread Summary
The discussion centers on the concept of entropy change in a resistor subjected to a constant current. Despite the resistor absorbing energy and generating heat, its entropy remains unchanged because its temperature and state do not vary during the process. The heat released into the environment increases the entropy of the surroundings, while the electrons in the circuit are responsible for the energy transfer. The resistor acts merely as a medium for heat transfer, with the entropy change occurring in the environment rather than the resistor itself. Ultimately, there is no distinguishable difference between resistors after current has flowed through one of them, as their intrinsic properties remain the same.
KFC
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There is an example in the textbook to show the change of entropy. A resistor being held at fixed temperature of 300K. 10 amp current passes through the resistor for 300 seconds. The change in entropy of the resistor is ZERO. The reason written in the book reads since the temperature doesn't change, the state doesn't change, so the entropy doesn't change.

I am very confuse about this statement ... if it is asking the change of entropy of gas, it is easy to understand, but now it is asking something like resistor, what does it mean by 'change of state'? Does it mean change of energy? If so, the resistor will absorb energy from the current and change some of them to heat, so the entropy of the resistor so be \Delta Q/T, \Delta Q is heat released and T is temperature.
 
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In what way is the resistor different after the current has flowed through it?
 
Vanadium 50 said:
In what way is the resistor different after the current has flowed through it?

But it release heat and work done.
 
heat flows into the environment, the entropy of the environment increases by δQ/T, T being the temperature of the environment.

The resistor doesn't really do anything, it is the electrons in the circuit that is doing all the work and producing heat. The resistor is merely a medium that does the heat transfer from electrons to the environment. Of course, the entropy of the electrons changes as well (it decreases).

This is the same thing as dropping a hot rock in water, the water becomes hot initially and does some work. However, at the end, when the water cools back down, there is no entropy change. It is the rock that ends up losing entropy and the environment ends up gaining it.
 
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KFC said:
But it release heat and work done.

Let me ask again. In what way is the resistor itself different after the current has flowed through it?

If I gave you two resistors, and I told you that one of them had current flowing through it yesterday and the other didn't, how could you tell them apart?
 

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