Understanding Maxwell's 4th Equation: Displacement Current Explained

  • Context: Undergrad 
  • Thread starter Thread starter Dx
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around Maxwell's fourth equation, specifically the concept of displacement current. Participants seek to clarify its meaning and implications, exploring both intuitive explanations and theoretical underpinnings.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant requests a simpler explanation of displacement current, expressing confusion despite having read the textbook definition.
  • Another participant notes that displacement current, alongside conduction current, contributes to the generation of magnetic fields, suggesting a connection between moving charges and magnetic effects.
  • A different participant introduces the idea that a magnetic field is a relativistic aspect of an electric field, implying that it arises from changes in the electric field or from the perspective of a moving observer.
  • One participant questions the necessity of the displacement current concept, suggesting it may have been a construct of Maxwell's pre-relativity understanding of electromagnetism.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and interpretation of displacement current, with some focusing on its role in generating magnetic fields while others question its conceptual foundation.

Contextual Notes

There are unresolved assumptions regarding the definitions and implications of displacement current, as well as the relationship between electric and magnetic fields in different reference frames.

Dx
Hello ppls,
i am reading my text and came across this interesting equation here.
my question is is simple lamens terms maxwells 4th equation: displacement current, how does it work in simple terms please. I ask cause I've read the definition and discussion in the book even though its concise I am a bitconfused of how it works other than its just a displacement of current.
Can anyone please explain this principle better.
Thanks!
Dx :wink:
 
Physics news on Phys.org
Originally posted by Dx
Hello ppls,
i am reading my text and came across this interesting equation here.
my question is is simple lamens terms maxwells 4th equation: displacement current, how does it work in simple terms please. I ask cause I've read the definition and discussion in the book even though its concise I am a bitconfused of how it works other than its just a displacement of current.
Can anyone please explain this principle better.
Thanks!
Dx :wink:

(My Physics book lists that one as the 3rd equation, but it makes no difference on how you number them.)
This equation is also known as Ampere's Law.
It basically means that both conduction current and displacement current act as sources of magnetic field.
Which makes sense since any moving electrons, or current, should be a source of magnetic field as long as it's in the correct (integration-)path.
 
DX, a magnetic field is just a relativistic part of moving electric field. Thus it is created by changing electric field (say, by moving electric charge, or just as appers to observer moving by stationary charge).

Magnetic field not a fundamental phyical field, but is just a mathematical result of Lorents transformation of coordinates for electric field from one reference system to another.

(Knowing this nature of magnetic field helps to understand its properties and its behavior better).
 
Last edited by a moderator:
Perhaps DX's problem is with the definition, or intuition, of displacement current? When I took EM (decades ago) that was a mystery wrapped up in an enigma; since I have learned the relativistic view of EM it doesn't seem necessary anymore. Can we learn to see it as just something Maxwell, trapped in the pre-relativity view, needed to pretend he thought existed?
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 13 ·
Replies
13
Views
7K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 26 ·
Replies
26
Views
7K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 0 ·
Replies
0
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K