# Propagation speed of the electrostatic field

• jeremyfiennes
In summary, the conversation discusses a thought experiment involving a proton and an electron and their interactions with each other. The proton exerts an electrostatic force on the electron and the charge of the proton is neutralized by firing another electron at it. The speed of light is mentioned as a factor in the experiment and the concept of a propagating electrostatic field is questioned. It is clarified that any change in the electric field will also affect the magnetic field and the distinction between electric and magnetic components depends on the chosen reference frame.
jeremyfiennes
I have a proton and an electron at a certain distance from it. The proton exerts an electrostatic force on the electron. I then neutralize the proton's charge by firing another electron at it from behind. How long does it take for the first electron to sense the change?

EM in a vacuum propagates at c, the speed of light.

However :
jeremyfiennes said:
I have a proton and an electron at a certain distance from it. The proton exerts an electrostatic force on the electron. I then neutralize the proton's charge by firing another electron at it from behind.
is a faulty description, the fields of the three particles effect each other at all distances and all directions. You can not suddenly make the net charge of the multi particle system vanish.

berkeman
That makes sense. Thanks.

berkeman
Also note that if a field changes, it's not static anymore. Then you have to use the retarded propagator to solve for the Maxwell equations, and that makes everything causal going with a speed less than or equal to the speed of light in a vacuum.

Ok. My doubt, however, is that this thought experiment refers to a propagating electrostatic, and not an electromagnetic field.

jeremyfiennes said:
Ok. My doubt, however, is that this thought experiment refers to a propagating electrostatic, and not an electromagnetic field.
If the electric field is changing (##\partial\vec E/\partial t\neq 0##) then the magnetic field is non-zero by the fourth Maxwell's equation.

There's an electromagnetic field, which usually is split up into electric and magnetic components, but this split depends on the chosen reference frame.

Ibix
I had suspected something like that. Thanks.

## 1. What is the propagation speed of the electrostatic field?

The propagation speed of the electrostatic field is the speed at which changes in the electric field spread through space. It is also known as the speed of light, which is approximately 299,792,458 meters per second in a vacuum.

## 2. How is the propagation speed of the electrostatic field related to the speed of light?

The propagation speed of the electrostatic field is equal to the speed of light because both phenomena are governed by the same fundamental laws of electromagnetism. This means that changes in the electric field propagate at the speed of light, regardless of the strength of the field.

## 3. Is the propagation speed of the electrostatic field affected by the strength of the electric field?

No, the propagation speed of the electrostatic field is not affected by the strength of the electric field. It remains constant at the speed of light regardless of the strength of the field.

## 4. Can the propagation speed of the electrostatic field be faster than the speed of light?

No, according to the theory of relativity, the speed of light is the maximum speed at which any physical phenomenon can travel. Therefore, the propagation speed of the electrostatic field cannot exceed the speed of light.

## 5. How does the propagation speed of the electrostatic field differ from the propagation speed of the magnetic field?

The propagation speed of the electrostatic field is the same as the propagation speed of the magnetic field. Both fields are part of the electromagnetic spectrum and are governed by the same fundamental laws of electromagnetism, resulting in the same propagation speed of light.

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