Why the current in a loop is the same

  • Context: Undergrad 
  • Thread starter Thread starter Gbox
  • Start date Start date
  • Tags Tags
    Current Loop
Click For Summary

Discussion Overview

The discussion centers on the behavior of current in a loop containing a DC source and two resistors connected in series. Participants explore the relationship between current and voltage across the resistors, as well as the implications of Kirchhoff's laws.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant suggests that the current in each resistor is different, proposing that the average current is considered in the loop.
  • Another participant argues that the current in each resistor must be the same due to the nature of series circuits, stating that the total voltage is equal to the sum of the voltages across each resistor.
  • A third participant notes that while the current is the same, the voltage across each resistor will differ, leading to a total voltage equal to the applied voltage.
  • Another participant questions the possibility of different currents at the node between the two resistors, referencing Kirchhoff's current law.

Areas of Agreement / Disagreement

Participants express disagreement regarding the nature of current in the resistors, with some asserting that the current is the same in a series circuit, while others propose that it could be different.

Contextual Notes

Participants have not resolved the implications of Kirchhoff's laws in this context, and there are differing interpretations of current behavior in series circuits.

Gbox
Messages
54
Reaction score
0
If for example we have in a loop a DC and 2 resistors connected in series, the current in each resistor is different ##I=\frac{V}{R_i}## but we say that the current is ##I=\frac{V}{R_1+R_2}##?

That means we are looking at the average current in a loop?
 
Physics news on Phys.org
Nope. The voltages over the each of the resistors is ##V_i = R_i I_i##, so ##
I_i=\frac{V_i}{R_i}## but the current in each resistor is the same (it has to go somewhere and it can't go anywhere else), so ##I = I_i\ \ \ \forall i##

Since ##V_i = R_i I_i = R_i I##, and ##V = \sum V_i## you get ##V = I (\sum R_i) \Rightarrow I = {V\over \sum R_i}##
 
  • Like
Likes   Reactions: Gbox
Voltage across each resistor will be different. The sum of the voltages will be total applied voltage V.
 
Gbox said:
2 resistors connected in series, the current in each resistor is different
apply Kirchoff's current law to the node between the two resistors. Is it possible for the currents to be different?
 

Similar threads

Undergrad DC current flows in a wire when two loops are brought close by?
  • · Replies 14 ·
Replies
14
Views
2K
Undergrad Expanding loop torque division
  • · Replies 3 ·
Replies
3
Views
349
Undergrad Energetic argument for the tension in a current loop
  • · Replies 8 ·
Replies
8
Views
1K
Undergrad Questions about cancelation of induced EMF and minimizing eddy currents
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Derivation of induced voltage in loop
  • · Replies 32 ·
2
Replies
32
Views
3K
High School Found a circuit where current is zero across an ohmic device (dV>0)
  • · Replies 11 ·
Replies
11
Views
1K
Undergrad Work Done in Changing Shape of Current Carrying Loop
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Charge movement relative to magnetic field frame dependence/invariance
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Is this example incorrect in Agawal's book on electric circuits?
  • · Replies 3 ·
Replies
3
Views
2K
Analyzing Bridge Circuit w/ Loop Currents
  • · Replies 6 ·
Replies
6
Views
2K