Circuit Questions -- Electrons flowing in wires and a resistor

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SUMMARY

This discussion centers on the behavior of electrons in a circuit with resistors, specifically addressing misconceptions about current flow and electron accumulation. Participants clarify that resistors do not inherently reduce current but affect it relative to other circuits. The conversation emphasizes that if electrons accumulate in one part of the circuit, they will repel each other, leading to a uniform charge density and consistent current flow throughout the circuit. The key takeaway is that current remains uniform despite the presence of resistors, as charge density adjusts to maintain equilibrium.

PREREQUISITES
  • Understanding of basic electrical concepts, including current and voltage.
  • Familiarity with Ohm's Law and its application in circuits.
  • Knowledge of electron flow and its relationship to current direction.
  • Basic principles of charge density and electric forces in circuits.
NEXT STEPS
  • Study the implications of Ohm's Law in complex circuits.
  • Learn about charge density and its effect on current flow in electrical systems.
  • Explore the role of resistors in series and parallel circuits.
  • Investigate the concept of electric fields and forces in relation to charge accumulation.
USEFUL FOR

Students of physics, electrical engineers, and anyone interested in understanding the dynamics of electron flow and current behavior in electrical circuits.

r0306
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Homework Statement



0d5e10c2b462ce173f383813dad18e6f.png

Homework Equations

The Attempt at a Solution


I have selected what I thought were the right choices in the original question. Resistors reduce current so electron flow should have been greater on the right. Also, the electrons flow opposite to current so potential is higher on the left. Potential energy is lost over resistors as heat so electrons have a higher potential energy when they start off but kinetic energy should not increase since energy was converted to heat instead.I am confused why my answer is wrong. Please help!
 
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r0306 said:

Homework Statement



0d5e10c2b462ce173f383813dad18e6f.png

Homework Equations

The Attempt at a Solution


I have selected what I thought were the right choices in the original question. Resistors reduce current so electron flow should have been greater on the right. Also, the electrons flow opposite to current so potential is higher on the left. Potential energy is lost over resistors as heat so electrons have a higher potential energy when they start off but kinetic energy should not increase since energy was converted to heat instead.

I am confused why my answer is wrong. Please help!
The answers in the figure are correct. Are those your answers?

Added in Edit:
Not all of those answers are correct.
 
SammyS said:
The answers in the figure are correct. Are those your answers?
Yes. That was what I put but my answers were incorrect.
 
SammyS said:
The answers in the figure are correct. Are those your answers?
r0306 said:
Yes. That was what I put but my answers were incorrect.
Sorry. I misread the Original Post.

If more electrons flow in the right hand wire than in the left hand wire, in what location do the excess electrons accumulate?
 
SammyS said:
Sorry. I misread the Original Post.

If more electrons flow in the right hand wire than in the left hand wire, in what location do the excess electrons accumulate?
Wouldn't they accumulate in the right hand wire then?
 
SammyS said:
Sorry. I misread the Original Post.

If more electrons flow in the right hand wire than in the left hand wire, in what location do the excess electrons accumulate?
I still don't get what this entails. Does this mean that current will be less in the resistor?
 
r0306 said:
Resistors reduce current so electron flow should have been greater on the right.
It's not that resistors reduce current in a circuit, but if you have two similar circuits and you add a resistor to one of them, then the current will be less than in the other circuit.

r0306 said:
Wouldn't they accumulate in the right hand wire then?
If electrons began accumulating somewhere, what do you think might happen?
 
Nathanael said:
It's not that resistors reduce current in a circuit, but if you have two similar circuits and you add a resistor to one of them, then the current will be less than in the other circuit.If electrons began accumulating somewhere, what do you think might happen?
This would cause a greater potential difference between that point and the end of the circuit.
 
  • #10
r0306 said:
This would cause a greater potential difference between that point and the end of the circuit.
I was thinking more on a small scale... if you have charges accumulating wouldn't you expect them to repel each other? This would cause the charges to spread back out if they began to accumulate.
 
  • #11
Nathanael said:
I was thinking more on a small scale... if you have charges accumulating wouldn't you expect them to repel each other? This would cause the charges to spread back out if they began to accumulate.
I'm having trouble putting this in perspective. If the charges spread back out, wouldn't they just push backwards towards the x direction?
 
  • #12
r0306 said:
I'm having trouble putting this in perspective. If the charges spread back out, wouldn't they just push backwards towards the x direction?
Which direction they push depends on which points you are considering. The main idea is that the charges resist accumulation. If they begin to accumulate, they will repel until the charge density is uniform again. I'm sure there are some technical points which are beyond me, but I'm just giving you a hand-wavey explanation of why the current tends to be uniform throughout a circuit.

If you meant that the charges will repel and then began accumulating in the opposite direction, well then the electric force would began opposing that accumulation. So which ever way it accumulates, the electric force tries to set it even again. Couple this with the fact that a non-uniform current implies a non-uniform charge density and the logical result is that current tends to be uniform throughout a circuit.
 
  • #13
Nathanael said:
Which direction they push depends on which points you are considering. The main idea is that the charges resist accumulation. If they begin to accumulate, they will repel until the charge density is uniform again. I'm sure there are some technical points which are beyond me, but I'm just giving you a hand-wavey explanation of why the current tends to be uniform throughout a circuit.

If you meant that the charges will repel and then began accumulating in the opposite direction, well then the electric force would began opposing that accumulation. So which ever way it accumulates, the electric force tries to set it even again. Couple this with the fact that a non-uniform current implies a non-uniform charge density and the logical result is that current tends to be uniform throughout a circuit.
I see what you mean now! Since current through a circuit is uniform, the number of electrons per second should not change either. Thank you!
 

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