Why Does Current Remain Constant in Series Circuit?

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Discussion Overview

The discussion revolves around the behavior of current in a series circuit, specifically addressing why the current remains constant despite the presence of resistors. Participants explore concepts related to charge flow, resistance, and the implications of adding more resistors to the circuit.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant states that current remains constant in a series circuit (I1=I2=I3) because charges do not accumulate at any point, despite the resistors having resistance.
  • Another participant compares current flow to a bicycle chain, suggesting that if the circuit is closed, all parts move at the same speed.
  • Some participants clarify that while resistors do not slow down the charges, they require a greater voltage to maintain the same current flow.
  • There is a discussion about the implications of unequal currents at different points in the circuit, with concerns about charge accumulation and the resulting electric fields.
  • Participants question whether adding more resistors in series would decrease current while maintaining its constancy throughout the circuit, and whether this would require an increase in voltage.
  • One participant emphasizes that resistors only cause potential drops and that to keep the current constant, the potential difference must be increased if more resistors are added.

Areas of Agreement / Disagreement

Participants generally agree that current remains constant in a series circuit, but there are differing views on the implications of adding resistors and the relationship between current and voltage. The discussion includes competing explanations and interpretations of how resistance affects current flow.

Contextual Notes

Some statements rely on assumptions about the behavior of electric fields and charge accumulation that are not fully explored. The discussion also touches on the definitions of current and voltage, which may vary among participants.

Who May Find This Useful

This discussion may be useful for students and enthusiasts of electrical engineering, physics, and anyone interested in understanding the principles of circuit behavior, particularly in series configurations.

Lim Y K
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The equation for current in series is I1=12=13 as the charges remain constant as it passes through the circuit regardless of the resistances of the resistors. i1 being the current before the resistor, i2 being the current after resistor 1 and i3 being the current after the last (2nd) resistor before going back to the battery. However, I=Q/T and since the resistors have resistance, the current will move slower through it. Wont this affect the current? why the current remains constant throughout the circuit (i1=i2=i3)?? can someone explain to me please?
 
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Current is like a bicycle chain. The whole thing moves, and all at the same speed, or it doesn't move at all (if you have an open circuit or a broken chain). That probably doesn't answer you question at the level of fundamental physics, but it IS the way it works.
 
Lim Y K said:
since the resistors have resistance, the current will move slower through it.

The charges don't slow down. Instead the resistance means that we have to push the charges harder to keep them moving at the same speed; that push comes from the voltage, which is higher at one end of the resistor than the other.
 
could you draw a circuit diagram? I am not sure what you mean by "current before" a resistor and after a resistor.
 
Chandra Prayaga said:
could you draw a circuit diagram? I am not sure what you mean by "current before" a resistor and after a resistor.
Think of a resistor drawn horizontally with the current flowing left to right. The left side is "before" the resistor and the right side is "after" the resistor.
 
Lim Y K said:
why the current remains constant throughout the circuit (i1=i2=i3)??
Ask yourself, what would happen if ##I_1 > I_2##. Specifically, what would happen to the charge on the first resistor?
 
DaleSpam said:
Ask yourself, what would happen if ##I_1 > I_2##. Specifically, what would happen to the charge on the first resistor?

there will be more chrage flowing through resistor one?
 
More than that. There will be charge accumulating in resistor 1. It will gain more and more net charge the longer the imbalance between the currents persists.

How long do you think any power source can push against the enormous E field that would be created by such a net charge?
 
oh so the reason why there's no charge build-up at any components of circuit is because the current remains the same throughout?
 
  • #10
Yes. If there were 1 A entering a resistor and 0.9 A leaving, then the resistor would be gaining 0.1 C every second. The E fields generated would quickly overwhelm any power source and crush any circuit material. The forces we are talking about are simply enormous.
 
  • #11
if more resistors are added into a circuit, the current will decrease but it will remain the same throughtout the circuit? or will more voltage be required to keep the current at the same speed?
 
  • #12
To your first question - Yes it will - if in series - Resistors only cause potential drop .

Current does not have speed . If you mean that you wish to keep the rate flow of charge constant
( current) , Yes you would have to increase the potential difference applied across the circuit by the battery or cell .
 
Last edited:
  • #13
Lim Y K said:
if more resistors are added into a circuit, the current will decrease but it will remain the same throughtout the circuit? or will more voltage be required to keep the current at the same speed?

If the resistors are added in series with other components, and the voltage is kept the same, then the current will decrease.
 

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