The Mystery of the Inductor's Initial Current

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Discussion Overview

The discussion revolves around the behavior of current in an electrical circuit involving an ideal inductor and its initial current when a switch is closed. Participants explore the implications of the inductor's properties, particularly in relation to current splitting at junctions and the assumptions made regarding ideal components.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that the initial current through the inductor is 20A, arguing that it does not split at junctions due to the inductor being ideal with zero resistance.
  • Others question whether any current enters the 0.1 ohm resistor branch, suggesting that if no current flows through it, then no current would flow through other resistors either, simplifying the circuit to just the current source and the inductor.
  • There is a suggestion that to model a real inductor, a series resistor could be added to the circuit sketch.
  • Some participants propose that if the inductor had a small resistance (e.g., 0.01 ohms), the current would then split between branches.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of current in the circuit, particularly regarding the implications of the inductor being ideal versus having resistance. The discussion remains unresolved with multiple competing perspectives on how current behaves in this scenario.

Contextual Notes

Assumptions about the ideal nature of the inductor and the implications of resistance in the circuit are not fully explored, leading to potential limitations in the discussion.

influx
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Why is the initial current through the inductor 20A? Surely the current splits at the junctions?
 
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It is an ideal inductor, it has a resistance of 0. The splitting still gives 20 A to the inductor.
 
mfb said:
It is an ideal inductor, it has a resistance of 0. The splitting still gives 20 A to the inductor.

So no current enters the 0.1 ohm resistor branch? Also, do we always assume its an ideal conductor in these types of questions?
 
influx said:
So no current enters the 0.1 ohm resistor branch?
Right.
Also, do we always assume its an ideal conductor in these types of questions?
To model a real inductor, we could simply add a series resistor in the sketch.
 
mfb said:
...

If no current passes through the 0.1 ohm resistor then I am assuming no current passes through the other resistors either? So effectively, when the switch is closed, the circuit consists of just the current source and the inductor?
 
mfb said:
Sure.

If the inductor did have some resistance, let's say 0.01ohms, would that mean that the 20A is split between branches?
 

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