What propagates changes of Coulomb force?

In summary: It is not related to the speed of light or any medium, since it is a result of Maxwells equations. In summary, the conversation discusses the propagation of electromagnetic information from a source charge at (0,0,0) to a point (l,0,0) with a time delay of l/c. The electric field at (l,0,0) is (a,0,0) at t<l/c and (b,0,0) at t>l/c, with a<b. There is a question about what substance carries this electromagnetic information, and the answer is the Lienard Wiechert potential, which is a solution to Maxwells equations. There is also a mention of the
  • #1
sweet springs
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Hi.

Say a positive charge is at (x,y,z)=(0,0,0) at t<0 then (1,0,0) at t>0.
Electric field at (x,y,z)=(l,0,0) is (a,0,0) at t<l/c then (b,0,0) at t>l/c thus a<b.

With time delay of l/c, what propagates from (x,y,z)=(0,0,0) to (l,0,0) ?
I do not think it is electromagnetic wave because it is not transverse but longtitudinal.

Electromagnetic wave by accerelation necessary for charge position change has nothing to do with my question, I guess.

Not charge position but charge velocity change causes similar propagation question.

Best
 
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  • #2
It is a kind of longtitudinal E-wave BUT it does not carry energy (the poynting vector for this wave is zero, because the resulting magnetic field doesn't cooperate with this longtitudinal wave).
 
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  • #3
sweet springs said:
Hi.

Say a positive charge is at (x,y,z)=(0,0,0) at t<0 then (1,0,0) at t>0.
Electric field at (x,y,z)=(l,0,0) is (a,0,0) at t<l/c then (b,0,0) at t>l/c thus a<b.

With time delay of l/c, what propagates from (x,y,z)=(0,0,0) to (l,0,0) ?
I do not think it is electromagnetic wave because it is not transverse but longtitudinal.

Electromagnetic wave by accerelation necessary for charge position change has nothing to do with my question, I guess.

Not charge position but charge velocity change causes similar propagation question.

Best
The specifics of this question are not answerable because it presupposes an unphysical movement.

However, with appropriate tweaking you could get a closely related question which would be physical. The answer to the closely related question would be the Lienard Wiechert potentials:

https://en.m.wikipedia.org/wiki/Liénard–Wiechert_potential
 
  • #4
Thanks Dale. The linked document of your recommendation says, "The force on a particle at a given location r and time t depends in a complicated way on the position of the source particles at an earlier time tr due to the finite speed, c, at which electromagnetic information travels."

My question should be translated to : What substance carries this "electromagnetic information" ?
EM wave carries information as radio or television do. Are there similar substance following a wave equation of speed c that carry electro magnetetic information used in Liénard–Wiechert potential?
Best
 
  • #5
sweet springs said:
What substance carries this "electromagnetic information"
Why should a substance be required? The aether is superfluous.

sweet springs said:
EM wave carries information as radio or television do. Are there similar substance following a wave equation of speed c that carry electro magnetetic information used in Liénard–Wiechert potential?
The Lienard Wiechert potential is a solution to Maxwells equations, just like any other classical EM field.
 
  • #6
Dear Dale.
Your answer to my question "what propagates electromagnetic information e,g, displacement of distant source charges with speed of c and how does it?" was "the LW potential that satisfies Maxwell equation". I still cannot leave from idea that something other than EM waves keeps radiated from the source charges with speed of light telling the information of the charge position. Is the LW potential reduced to microscopic relation explicitly containing c? Is the LW potential is unchanged if EM media is inserted between ? I keep thinking about it by myself and ask again if it makes sense. Thank you so much for now.
 
  • #7
sweet springs said:
I still cannot leave from idea that something other than EM waves keeps radiated from the source charges with speed of light telling the information of the charge position.
Please review the forum rules about personal speculation before pursuing this line of discussion here.

sweet springs said:
Is the LW potential reduced to microscopic relation explicitly containing c? Is the LW potential is unchanged if EM media is inserted between ?
You can read the derivation of the LW potential right there on the Wiki page, and in any halfway decent textbook. Including the online ones from MIT and UT.
 

FAQ: What propagates changes of Coulomb force?

1. What is the Coulomb force?

The Coulomb force, also known as electrostatic force, is a fundamental force of nature that describes the attraction or repulsion between two charged particles. It is similar to the gravitational force, but acts between charged particles instead of masses.

2. How is the Coulomb force calculated?

The Coulomb force is calculated using Coulomb's law, which states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. The formula is F = k(q1q2)/r^2, where F is the force, q1 and q2 are the charges of the particles, r is the distance between them, and k is the proportionality constant.

3. What factors affect the strength of the Coulomb force?

The strength of the Coulomb force is affected by two main factors: the magnitude of the charges and the distance between them. The greater the charges, the stronger the force, and the closer the particles are, the stronger the force.

4. How does the Coulomb force change with distance?

The Coulomb force follows an inverse square law, which means that as the distance between two charged particles increases, the force decreases by a factor of four. This means that the force decreases rapidly as the distance between the particles increases.

5. What are some real-world applications of the Coulomb force?

The Coulomb force plays a crucial role in many aspects of our everyday lives. It is responsible for the interactions between atoms and molecules, which determine the properties of matter. It is also the force behind many technological applications, such as electricity and magnetism, as well as medical applications like MRI machines and defibrillators. Additionally, the Coulomb force is essential in understanding and predicting the behavior of charged particles in the universe, such as the movement of charged particles in the Earth's atmosphere.

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