How Do Electrons Distribute Energy in a Circuit with Multiple Resistors?

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Discussion Overview

The discussion centers on how electrons distribute energy in a circuit with multiple resistors, particularly focusing on the behavior of electrons in relation to the electric field and potential drops across resistors. The scope includes conceptual understanding and analogies to clarify the underlying physics.

Discussion Character

  • Conceptual clarification
  • Exploratory

Main Points Raised

  • One participant questions how electrons "know" to distribute their energy between resistors in a circuit, specifically when a second identical resistor is added.
  • Another participant explains that electrons respond to the electric field and do not "save" energy, but rather transfer energy to thermal energy upon colliding with lattice molecules in the resistor.
  • A further inquiry is made about whether the presence of the new resistor alters the electric field, affecting the energy dissipated in the first resistor.
  • One participant provides an analogy of water flowing down a slope to illustrate how potential difference influences flow dynamics, emphasizing that the system's behavior is determined by the potential difference rather than the electrons' awareness.
  • A later reply confirms that the presence of the new resistor does indeed alter the electric field, leading to a change in energy dissipation across the resistors.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the behavior of electrons and the influence of resistors on energy distribution. While some concepts are clarified, there is no consensus on the exact mechanisms at play, leaving the discussion open-ended.

Contextual Notes

Participants rely on analogies and conceptual reasoning, with some assumptions about the behavior of electric fields and energy transfer that may not be fully resolved. The discussion does not delve into mathematical formulations or detailed circuit analysis.

broegger
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I have a somewhat simple question, that I for some reason can't figure out..

suppose you have a circuit with a source of emf (e.g. a battery).. if you put a single resistor in this circuit there is a potential drop equal in size to the emf (i neglect internal resistance in the source).. now, if you place a second, identical resistor in the circuit the potential drop over the first resistor will be exactly half of it's initial value (that is, 1/2*emf).. my question is: how does the electrons "know" only to put half their energy in the first resistor and save the other half for the second - how does they detect the presence of the new resistor?

I'm sure I should know this, but my book doesn't offer any explanation..
 
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Originally posted by broegger
.. my question is: how does the electrons "know" only to put half their energy in the first resistor and save the other half for the second - how does they detect the presence of the new resistor?
All the electrons know about is the electric field that pulls them along. They don't "save" energy. Imagine gazillions of electrons being jerked along through the resistor by the electric field. Each electron doesn't get far before it smacks into a lattice molecule, thus transfering its energy to thermal energy of the resistor. But then the electron once again gets accelerated by the field... until it smacks into the lattice again. Etc.
 
Thank you.. so the presence of the new resistor somehow alters the electric field, so that the dissipated energy in the first resistor drops to the value corresponding to 1/2*emf??
 
Maybe another simpler way to visualize this is to think about the analogy of water flowing. If you dump a bucket of water out of a window, let say 100 meters above the ground, it falls easily to the ground .. SPLASH!

But, if you take that bucket of water to a height of 100 meters and pour it on a rocky slope, it takes some time to reach the ground, but it eventually does (ignoring evaportaiton of course).

So, if this rocky slope is in TWO portions, with a free fall between them, you have little trouble visualizing the water flowing through the first part .. falling freely to the second stage, and resuming its journey until it is all at the bottom.

All it KNOWS is the potential difference and the flwo dynamics result from that alone.

Regards
 
Originally posted by broegger
...so the presence of the new resistor somehow alters the electric field, so that the dissipated energy in the first resistor drops to the value corresponding to 1/2*emf??
Right.
 

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