# Experiment for the existence of electrostatic field

• alan123hk
In summary, the classical electromagnetic theory suggests that an electrostatic field can be created by an electrically charged particle, but this field does not stop close to the particle but extends to the universe. However, no experiment has ever been conducted to show that this field actually exerts a force on another charged particle located very far away.
alan123hk
I am still puzzled by the issue of existence of electrostatic field.
According to the classical electromagnetic theory, electrostatic field can be created by an electrically charged particle. The electrostatic field surrounding the electrically charged particle does not stop close to the particle but extends to universe. This electrostatic field exerts a force on another electrically charged object millions km away experience a force immediately, which seems to be something faster than light.

My question is: has any experiment ever been conducted to prove that the electrostatic field actually exert the force immediately or not to another charged particle located very far away?

This should be a simple and straightforward way to prove the existence of the electrostatic field, isn't it?
It seems no technical difficulty for this experiment.

I apologize if this is a pretty ignorant question.

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tech99
One must note that an electrostatic field is, by definition, unchanging. So the question of whether its effects at a distance are immediate, delayed or even proactive does not arise. If we are to talk about how changes propagate, we are no longer talking about static fields.

Electric charge is a conserved quantity. One cannot simply create a charge out of thin air and watch how its field propagates over time. What one can do is to wiggle a charge around and watch how the resulting field changes propagate. The result is radio waves. They are a form of electromagnetic radiation and propagate at the speed of light. Light, too, is a form of electromagnetic radiation. Just a much higher frequency.

Maxwell's Equations (from James Clerk Maxwell around the time of the U.S. civil war) describe the way the field behaves and how field changes propagate. His equations are a set of differential equations. The equations have solutions which include waves moving at the speed of light.

Albert Einstein created his famous Theory of Relativity which showed these equations could successfully work and allow for a speed of light that is seen to be the same no matter how fast you are moving when you measure it.

So to answer your question: Yes, we've measured it and found that changes propagate at the speed of light, just as theory predicts.

anorlunda and Dale
alan123hk said:
This electrostatic field exerts a force on another electrically charged object millions km away experience a force immediately

That is simply incorrect, so of course there is no experiment that demonstrates it.

jbriggs444 said:
Electric charge is a conserved quantity. One cannot simply create a charge out of thin air

But one can create a static or oscillating electric dipole in the space which resulting in a static or oscillating electric field surrounds it, am I right ?
I believe that an electric dipole may be created momentarily in the space to test whether the space has been occupied or not by an electrostatic field, is it possible ?

alan123hk said:
But one can create a static or oscillating electric dipole in the space which resulting in a static or oscillating electric field surrounds it, am I right ?
I believe that an electric dipole may be created momentarily in the space to test whether the space has been occupied or not by an electrostatic field, is it possible ?
Certainly one can create a dipole. This creates a propagating disturbance in the field.

https://en.wikipedia.org/wiki/Dipole_antenna

jbriggs444 said:
Certainly one can create a dipole. This creates a propagating disturbance in the field.

Then we can prove the so-called electrostatic field in classic electromagnetism may not actually exist if the electric dipole does not experience a torque force immediately, Is it correct?

alan123hk said:
Then we can prove the so-called electrostatic field in classic electromagnetism may not actually exist if the electric dipole does not experience a torque force immediately, Is it correct?
No, you would show that changes of the field propagate at a finite speed.

jbriggs444
As was pointed out in the first response in this thread, a changing electrostatic field is a contradiction in terms. If you contemplate changes, you are talking dynamics, not statics.

An electrostatic field is a fine approximation for a situation where the field is changing slowly enough or measurements are sloppy enough that propagation times are negligible. It is not a good approximation if you are trying to measure the field change propagation rate and you have instruments good enough to notice the finite speed of light.

A.T. said:
No, you would show that changes of the field propagate at a finite speed.

Does it mean that no force will be immediately applied to the electric dipole ?

If the answer is "Yes", then I think this is a proof of non-existence of electrostatic field, or it is just a approximation model.

In fact, I did not try to prove here the concept that the electrostatic field immediately produces a remote influence. I only want the answer. That's why I said that I am still confused about the problems in the electrostatic field.

Anyway, I want to thank everyone for teaching me so many things.

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alan123hk said:
Then we can prove the so-called electrostatic field in classic electromagnetism may not actually exist if the electric dipole does not experience a torque force immediately, Is it correct?

You are ignoring the "static" portion of electrostatic, and trying to apply it to electrodynamic problems. I think that contradiction is causing your confusion.

alan123hk said:
I am still puzzled by the issue of existence of electrostatic field.
According to the classical electromagnetic theory, electrostatic field can be created by an electrically charged particle. The electrostatic field surrounding the electrically charged particle does not stop close to the particle but extends to universe. This electrostatic field exerts a force on another electrically charged object millions km away experience a force immediately, which seems to be something faster than light.

My question is: has any experiment ever been conducted to prove that the electrostatic field actually exert the force immediately or not to another charged particle located very far away?

This should be a simple and straightforward way to prove the existence of the electrostatic field, isn't it?
It seems no technical difficulty for this experiment.

I apologize if this is a pretty ignorant question.

I do not understand this question. Are you saying that you doubt that like-charges repel and unlike-charges attract, i.e. you think that static cling is due to something else?

If you do not see the connection between my question, and the existence of electric field, then we have a separate issue.

Similarly, do you also doubt the existence of gravitational field? Just like electric field from a point charge, gravitational field from a body extends to infinity.

Zz.

bhobba
alan123hk said:
... or it is just a approximation model...
All models in physics are idealizations. Applying them to not perfectly ideal real world scenarios is called approximation.

A.T. said:
All models in physics are idealizations. Applying them to not perfectly ideal real world scenarios is called approximation.

Therefore, Newton's law of gravitation is also an idealized model, applying it to not perfectly ideal real world scenarios is called approximation.

alan123hk said:
Therefore, Newton's law of gravitation is also an idealized model, applying it to not perfectly ideal real world scenarios is called approximation.
Yes, so?

alan123hk said:
or it is just a approximation model.
Yes. If you do a calculation involving a field that is not changing then there is a built in caveat about the length of time that the field can be considered as being static. You seem to be doing nothing more than trying to challenge the validity of a commonly used approximation and that is a pretty pointless activity. If the field has not changed for a time that's sufficient for the experiment or model then you can call it Static. This is a common principle in all Classical Physical Theories and it has stood the test of History. If you need to include the life of the Universe in any particular theory then 'static' would be a forbidden term, I think.

alan123hk said:
This electrostatic field exerts a force on another electrically charged object millions km away experience a force immediately, which seems to be something faster than light.
@anorlunda pointed out what you've missed in post #10 - you are conflating electrostatics and electrodynamics.

An electrostatic field is static - it's not changing over time. That's we call it electrostatic.

To produce an electrostatic field, first we position our charges in whatever fixed positions we're interested in. This of course causes changes in the electric field as we move the charges into position; that's not a static situation so we use the more complicated methods of electrodynamics (the equation of electrostatics are a special case of these - set the rate of change to zero in the electrodynamic equations and they simplify down to electrostatics) and find that the changes in the field propagate at the speed of light and no faster.

Then we wait... we wait... until the changes in the field have propagated and everything has settled down into a static configuration in whatever region of space we're interested in. So the answer to your question about how the electrostatic field from particle A can create a force at point B millions of kilometers from particle A is that the field is already there - That's why it's an electrostatic situation.

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Vanadium 50, bhobba, anorlunda and 2 others
If I have a charge that is mechanically vibrating in the direction to-and-from me, I do not expect to see a radiated field, which would be parallel to the acceleration. But I would still expect to observe a fluctuating radial electric field. My test charge will move forward and back. In this case maybe we could measure the propagation delay of the radial electric field. I would be interested in the view on this.

alan123hk
alan123hk said:
I am still puzzled by the issue of existence of electrostatic field.
According to the classical electromagnetic theory, electrostatic field can be created by an electrically charged particle. The electrostatic field surrounding the electrically charged particle does not stop close to the particle but extends to universe. This electrostatic field exerts a force on another electrically charged object millions km away experience a force immediately, which seems to be something faster than light.

My question is: has any experiment ever been conducted to prove that the electrostatic field actually exert the force immediately or not to another charged particle located very far away?

This should be a simple and straightforward way to prove the existence of the electrostatic field, isn't it?
It seems no technical difficulty for this experiment.

I apologize if this is a pretty ignorant question.
Alan, here is a gif type visual demonstration of the relationship of changing electrostatic vs electromagnetic fields. It may help you understand:
https://micro.magnet.fsu.edu/primer/java/polarizedlight/emwave/index.html

The two effects, magnetic and static waves (waves being only caused by change, or disturbance) are perpendicular to one another. The change in this case is the cycling applied by a generator or transmitter.

You are somewhat correct that the electrostatic effect is instantaneous in a way. A charged particle, such as an electron, forms a continuous static force that extends indefinitely in space, so that all other charged particles are in a sort of instantaneous connection, somewhat like an ordinary rubber rope connection. However, it is better to think of the connection as limited to the speed of light because any change in an electron in your hand does not affect, say a nearby star, until the change has traveled to the star, just like a "traveling" jerk on a rubber rope. The change cannot travel faster than light, both proven by Maxwell's formulas and the initially baffling results of excruciating multiple measurements made by Michelson-Morley.

Each radio transmission contains both electrostatic and electromagnetic fields and a common dipole antenna (and AM radio receiver) may be easily used to detect a change in either field... but not so much in a static non-changing/non-moving field. Fortunately a charged surface, such as a charged leaf of foil, or a charged balloon, may detect a non-moving strong static field by it's tendency to move away, or towards, the charged object or direction in question. Because of the rapid exponential loss of static field strength (inversely proportional to distance), we would need a more sensitive amplified version of such "scientific instruments" to detect a non-moving/non-changing static charge as far away as a even a close neighbors yard however.

Wes

Wes Tausend said:
Alan, here is a gif type visual demonstration of the relationship of changing electrostatic vs electromagnetic fields.

That gif is of an electromagnetic wave, which consists of varying electric and magnetic field vectors. In other words, it is a dynamic situation and not a static one. So no, it is not an electrostatic vs electromagnetic field.

Wes Tausend said:
The two effects, magnetic and static waves (waves being only caused by change, or disturbance) are perpendicular to one another.

I think you are confusing electric with static. Both electric and magnetic fields can be dynamic or static.

Wes Tausend said:
You are somewhat correct that the electrostatic effect is instantaneous in a way.

I don't quite agree. It makes little sense to ask how long it takes for the force from an electrostatic field to act on a particle, as it is already acting on that particle. There is no situation in which you have an electrostatic field, a test charge, and a time before or after the force acts. The only possible situation is one in which the force is acting on the charge. Once you start talking about changes and delays you have a dynamic field, not a static one.

davenn
Drakkith said:
That gif is of an electromagnetic wave, which consists of varying electric and magnetic field vectors. In other words, it is a dynamic situation and not a static one. So no, it is not an electrostatic vs electromagnetic field.
I think you are confusing electric with static. Both electric and magnetic fields can be dynamic or static.
I don't quite agree. It makes little sense to ask how long it takes for the force from an electrostatic field to act on a particle, as it is already acting on that particle. There is no situation in which you have an electrostatic field, a test charge, and a time before or after the force acts. The only possible situation is one in which the force is acting on the charge. Once you start talking about changes and delays you have a dynamic field, not a static one.

You are quite correct on both counts, Drakkith.

I unintentionally misstated electric for static in the first example.

And your point in the second example is a much more elegant way of describing the observation of a undisturbed presently-acting electrostatic force than was my clumsy attempt. It is only the varied electrostatic disturbance of one object that must travel, which is indeed a dynamic effect. And this varied electrostatic disturbance will travel limited to the maximum speed of light in a vacuum. Hope I have it correct now.

Thank you,
Wes

Drakkith
Wes Tausend said:
And this varied electrostatic disturbance will travel limited to the maximum speed of light in a vacuum.

It's just an electric disturbance, not an electrostatic disturbance.

After all of these misstatements, corrections, wrong usage of phrases, etc... etc... what exactly is the original question now?

Zz.

davenn and anorlunda

## 1. What is an electrostatic field?

An electrostatic field is a region in space where electrically charged particles experience a force. This force is caused by the electric charges interacting with each other.

## 2. How can you conduct an experiment to demonstrate the existence of an electrostatic field?

One way to conduct an experiment is to use a charged object, such as a balloon rubbed against hair, and observe how other objects, such as small pieces of paper, are attracted to or repelled by the charged object. This demonstrates the presence of an electrostatic field.

## 3. What materials are needed for an experiment on the existence of an electrostatic field?

The materials needed may vary depending on the specific experiment, but generally, you will need a charged object, such as a balloon or comb, and small, lightweight objects to observe the effects of the electrostatic field on them.

## 4. How does the strength of an electrostatic field vary with distance?

The strength of an electrostatic field decreases as the distance from the source increases. This is known as the inverse-square law, which states that the strength of the field is inversely proportional to the square of the distance from the source.

## 5. What are some real-world applications of understanding electrostatic fields?

Understanding electrostatic fields is important in various fields, such as engineering, electronics, and even in everyday life. Some applications include the design of electronic devices, air pollution control, and the development of new technologies, such as electrostatic precipitators used in power plants to remove particulates from exhaust gases.

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