Understanding Maxwell's 4th Equation: Displacement Current Explained

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In summary, the conversation discusses Maxwell's fourth equation, also known as Ampere's Law, and the concept of displacement current. The equation states that both conduction current and displacement current act as sources of magnetic field, with the latter being a result of Lorentz transformation. The concept of displacement current may be difficult to grasp, but understanding its nature as a relativistic part of moving electric field can help clarify its properties and behavior. Some argue that displacement current is not a necessary concept and was simply included by Maxwell in his pre-relativity view.
  • #1
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:
 
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  • #2
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.
 
  • #3
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).
 
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  • #4
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?
 

What is Maxwell's 4th equation?

Maxwell's 4th equation, also known as the Maxwell-Ampere equation, is one of four equations that make up James Clerk Maxwell's theory of electromagnetism. It describes the relationship between the electric current and changing electric fields.

What is displacement current?

Displacement current is a concept introduced by Maxwell in his 4th equation. It is a type of electric current that arises from the changing electric fields in a region of space, rather than from the movement of physical charges. It is a crucial component of electromagnetic waves.

How does displacement current differ from conduction current?

Displacement current and conduction current are two types of electric current that exist in different scenarios. Conduction current is the flow of electric charges through a medium, such as a wire. Displacement current, on the other hand, is a type of electric current that arises from changing electric fields in a vacuum or insulating material.

Why is displacement current important?

Displacement current is important because it is a fundamental concept in electromagnetism and is essential for the understanding of how electromagnetic waves are generated. It also helps to explain the behavior of electric and magnetic fields in various situations, such as in the creation of radio waves and in the functioning of capacitors and inductors.

What are the practical applications of understanding Maxwell's 4th equation?

Understanding Maxwell's 4th equation and displacement current has led to numerous practical applications in various fields, including telecommunications, electronics, and medical imaging. It has also played a crucial role in the development of technologies such as radio, television, and wireless communication. Additionally, it has furthered our understanding of the fundamental laws of electromagnetism and has paved the way for advancements in other areas of science and technology.

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