On Electric Fields...

Discussion in 'Physics' started by turkey3_scratch, May 10, 2016.

  1. turkey3_scratch

    Thread Starter New Member

    Apr 15, 2016
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    Okay, so let me get this straight with some questions.

    1) Does an electric field only exist between individual protons and neutrons? If so, then if there is an object (say a newspaper) with a negative charge and another object with a positive charge, is that strong electric field between the two a combination of a bunch of individual electric fields, or does an actual, collaborative group of charges create one unified electric field? Is there a big daddy or a bunch of little bros?
    2) I understand that an electric field is defined at every point in space. However, what I don't know is if there are, in a sense, multiple electric fields or does all of space have one, huge, warped electric field?
    3) If the answer to #2 is that there is not a single electric field, what happens when electric fields overlap, for instance? What about a particle caught in the middle?
    4) Does an electric field exist independently of matter? Or is an electric field more of a conceptual label of how certain charge interact with one another? Basically what I'm saying is do these fields truly exist, or are they only abstract concepts to describe how negative and positive particles accelerate and their behavior?

    Thank you for your time. It is extremely complex stuff to understand, so I need all the help I can get.
     
  2. crutschow

    Expert

    Mar 14, 2008
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    Neutrons don't have an electric field (hence their name) but protons and electrons do.
    An electric field is the sum of all the individual fields of all the charged particles in the neighborhood.
     
  3. turkey3_scratch

    Thread Starter New Member

    Apr 15, 2016
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    So it is collective, as per #1? Also, wouldn't that sort of be a paradox? If an electric field is defined as the sum of those smaller fields, then how would we define those smaller, individual fields of the charged particles in the neighborhood?

    Anyway, I get the jist of what an electric field is. Just have trouble with more specifics like #2 #3 and #4.
     
  4. DGElder

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    Apr 3, 2016
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    The answer to #4 depends on whether you take the Blue pill or the Red pill.
     
  5. nsaspook

    AAC Fanatic!

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    "All measurable results to date are consistent with its existence." It carries momentum and energy.

    "really exists" is a philosophical question of a vast cosmic conspiracy trick.
     
  6. turkey3_scratch

    Thread Starter New Member

    Apr 15, 2016
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    Okay, so if I'm correct, every charge in this universe pulls on every oppositely charged charge (and repels all alike charges). So does every charge inflict some drift or velocity on every other charge, even if it is something like 1.00 x 10^-5000 m/s (as in an electron's field reaching light years across space to a proton).
     
  7. SLK001

    Well-Known Member

    Nov 29, 2011
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    Yes... Just like gravitational fields.
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    No. An electric field can also exist separate from any charge distribution. To be specific, a changing magnetic field induces an electric field.

    The value of the electric field at any point in space is the superposition of all of the electric fields from all of the sources. This is assuming that the point in question is within a linear medium -- field behavior in nonlinear media is a very different critter.

    Either view is acceptable -- the only difference is how you choose to view things. But where you should start is with understanding Coulomb's Law which explicitly describes the force on one charged particle due to another. Then understand that if we have multiple other charged particles that we can describe the net force on the first as a sum of forces due to all of the others. Then we can simply recognize that the net force is the product of two things -- the sum of bunch of terms that are due to all of the other charges and a factor that is due to the charge that the force is acting on. By definition, we call the sum of the bunch of terms due to all of the other charges the "electric field" at that point. There really isn't anything more magical or mysterious about it.

    If the medium is linear, the value of the electric field at any point is the sum of all of the electric fields from all of the sources at that point.

    What do you mean by "a particle caught in the middle"?

    What does it mean "to truly exist"? They are mathematical constructs that are as real, or not real, as just about any other mathematical construct.
     
  9. DGElder

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    Apr 3, 2016
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    "No. An electric field can also exist separate from any charge distribution. To be specific, a changing magnetic field induces an electric field."

    And where did the magnetic field come from? It came from the motion of charge. There is no magnetic monopole. An E-field will always require the presence of charge.
     
  10. WBahn

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    Light is nothing but an electromagnetic wave consisting of coupled electric and magnetic fields -- a changing magnetic field induces a changing electric field that induces a changing magnetic field and so on. Even if you want to claim that the light started out as a result of charged particles, you have to contend with the fact that the fields we interact with today might have been launched well over ten billion years ago from ten billion light years away. It becomes pretty hard to maintain that an E-field always requires the presence of charge under that reality.
     
  11. BR-549

    Well-Known Member

    Sep 22, 2013
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    "1) Does an electric field only exist between individual protons and neutrons?"

    An electric field is like a thick peeling around the charge. Some like to call it a charge extension. The proton has 1 positive charge and 1 positive electric field. Positive fields do not travel out, and negative fields do not travel in, as taught. As a positive field proceeds, it will rotate to the right. A positive field has right handedness. A negative field is left handed. As it proceeds, it will rotate left.

    Handedness is what causes repulsion and attraction. A right handed auger and a left handed auger will fit together. Two right handed augers will not.

    The neutron has two electric fields, one positive and one negative. These bonding of these two fields help hold the neutron together and are not available for external bonding. Therefore, the only bonding between a proton and neutron is the magnetic bond.

    "If so, then if there is an object (say a newspaper) with a negative charge and another object with a positive charge, is that strong electric field between the two a combination of a bunch of individual electric fields, or does an actual, collaborative group of charges create one unified electric field? Is there a big daddy or a bunch of little bros?"

    It's always a bunch of little ones. BUT.....at the same time, it does not mean you have to have a bunch of little ones. For instance......the power company will have a vast store of charge to generate a high voltage. I can use that voltage to move a few electrons at high voltage, without accumulating the charge at my house. The accumulated voltage can be given to a few charges.
    It's like pressure, because it is a physical charge pressure.

    "2) I understand that an electric field is defined at every point in space. However, what I don't know is if there are, in a sense, multiple electric fields or does all of space have one, huge, warped electric field?

    Both, because space in linear. Even in areas of low particle density, there are billions of particles fields that permeate space. And because of superposition, there is a constant flowing net electric field. Same of course for the magnetic.

    "3) If the answer to #2 is that there is not a single electric field, what happens when electric fields overlap, for instance? What about a particle caught in the middle?"

    The particle will change velocity. Velocity is speed AND/OR direction.

    "4) Does an electric field exist independently of matter? Or is an electric field more of a conceptual label of how certain charge interact with one another?"

    YES, but ONLY with emission. An emitted wave is the only example.

    "Basically what I'm saying is do these fields truly exist, or are they only abstract concepts to describe how negative and positive particles accelerate and their behavior?"

    Two charged spheres, two magnets and a piece of cardboard can show most people that the two fields exist and that they are not composed of matter. And that they exert force.
    It's convincing to me.

    The charge field, the peeling around the charge, controls behavior.
     
  12. DGElder

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    Apr 3, 2016
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    "......you have to contend with the fact that the fields we interact with today might have been launched well over ten billion years ago from ten billion light years away. It becomes pretty hard to maintain that an E-field always requires the presence of charge under that reality"


    As you put it: "they are mathematical constructs that are as real, or not real, as just about any other mathematical construct"

    If it makes you feel better, look at it from the perspective of the photon; because it travels at the speed of light no time has passed and no space has been spanned due to infinite time dilation and space contraction.
     
    Last edited: May 12, 2016
  13. WBahn

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    Mar 31, 2012
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    And,by carefully choosing your reference frame, you can show that there is no such thing as a magnetic field. So questions like this become very tricky.
     
  14. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    That one body may act upon another at a distance, through a vacuum, without the mediation of anything else… is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. – Isaac Newton

    Deeper down the rabbit hole: Isaac Newton seems to have believed fields existed. What if particles are just excitations of universe wide fields.

     
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