Capacitors, Entropy & Energy Loss

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    Capacitors Entropy
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Discussion Overview

The discussion revolves around the relationship between capacitors, entropy, and energy loss in electrical circuits. Participants explore how energy dissipation in capacitors and resistive components, like light bulbs, relates to the concept of entropy, considering both theoretical and practical implications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the energy loss from a capacitor when connected to a light bulb can be attributed to an increase in entropy, suggesting that this aligns with their understanding of natural processes.
  • Another participant provides a definition of entropy, indicating that while entropy may play a role, electromagnetic forces are likely the dominant factor in the energy transfer from the capacitor.
  • A different participant emphasizes that the energy loss from the capacitor is not solely due to entropy, noting that actual energy loss is influenced by resistance in the circuit, including the capacitor itself.
  • It is suggested that entropy is a result of energy losses leading to temperature changes, with a positive change in entropy indicating energy loss and temperature drop in one system, while another system may experience a temperature rise.
  • One participant asserts that entropy is a description of energy processes rather than a causal mechanism.
  • A participant introduces the concept of an LC-tank circuit, explaining that energy oscillation between an inductor and capacitor can occur, with entropy remaining constant in an ideal scenario, but eventually increasing due to real-world resistance.

Areas of Agreement / Disagreement

Participants express differing views on the role of entropy in energy loss from capacitors, with some suggesting it is a contributing factor while others argue it is not the primary cause. The discussion remains unresolved regarding the precise relationship between entropy and energy dissipation in this context.

Contextual Notes

Participants reference various assumptions about energy loss mechanisms, the definitions of entropy, and the behavior of ideal versus real-world circuits, which may affect their arguments.

RobinSky
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I was thinking of this following example:

Consider you charge a capacitor to its max with a battery, now replace the battery with a light bulb for example. The capacitor is starting to lose all the energy it had stored, is this a result due to entropy?
I mean I've learned that an increase in entropy is a natural process, and for me, when the capacitor is losing it's energy, the system gets an increase in entropy, right? Same goes with common batteries, leave them to be (whether in use or not), and after enough time they are not usable anymore. So is it okay to see this as a result due to entropy?

Regards, Robin.
 
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None? :/
 
Entropy is defined as kln(Ω) where k is Boltzmann's constant, ln() is the natural logarithm function, and Ω is the number of different ways that a system can have particular values of whatever properties one is concerned with (i.e., the ones you are measuring).

While I imagine that the thermodynamic tendency to increase entropy could contribute the current produced when the battery is replaced, I would think that the electromagnetic forces involved would dominate under ordinary circumstances. That is, the attraction of opposite charges (the opposing surfaces in a capacitor are oppositely charged) is the main cause of the motion of the electrons.
 
RobinSky said:
I was thinking of this following example:

Consider you charge a capacitor to its max with a battery, now replace the battery with a light bulb for example. The capacitor is starting to lose all the energy it had stored, is this a result due to entropy?

The energy given off by the capacitor is not identical to the actual loss of energy. The actual loss of energy depends on how much energy was dissipated as resistance. Part of the resistance can be in the capacitor, and the most of the rest is dissipated in other parts of the circuit.

RobinSky said:
I mean I've learned that an increase in entropy is a natural process, and for me, when the capacitor is losing it's energy, the system gets an increase in entropy, right?

The entropy is based on energy losses that lead to a temperature change in the system. A positive change in entropy means a loss of energy and a drop of temperature for a system. You also have an energy increase and temperature rise for another system. It's the cooling process for one system and the heating process for another, that determines the entropy.

RobinSky said:
Same goes with common batteries, leave them to be (whether in use or not), and after enough time they are not usable anymore. So is it okay to see this as a result due to entropy?

Regards, Robin.

Entropy is the result of that, not the cause of that. Entropy is a description - not a mechanism.
 
It's a very good question. Thanks, I learned a lot.
 
Thanks for the replies guys! I say, as the person above, I learned a lot! There might be a few more follow-up questions from me the comin' days though!
 
Entropy increase happens in the resistor (light bulb in this case), not in capacitor. If you connect inductor instead, you will get an LC-tank. The energy will oscillate back and forth between inductor and capacitor. Ideal LC tank would oscillate indefinitely and the entropy would stay the same. In the real world oscillations will eventually die out and the energy will be converted into heat (with corresponding increase in entropy) due to the resistance of the wires including those in the inductor and capacitor.
 
Ah! That was a good "analogy", thanks again for a good answer.
 

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