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# what is the difference between an electrical field and a magnetic field?

Posted on 2014-02-08
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Hello and Good Evening Everyone,

I am wondering what the difference is between an electrical field and a magnetic field.  From a brief discussion with a friend of mine who is a physics major, he says that an electrical field is made up of atomic particals called electrons.  Now, when these electrons are in movement, it creates what is called a magnetic field.  He also added in an example of a bar magnet, electrical coil with a battery hooked up to it, and a compass.  At that part is when I became lost and was not following how this example fit it.  I am sure he was explaining it well, but, it was hard for me to make the connections necessary to differentiate between and electrical and magnetic field.  I guess you could say I am more of a tangiable learner as opposed to a conceptual learner.  At any rate, could someone explain the difference or differences between an electrical field and a magnetic field using the examples of a bar magnet, electrical coil with a battery hooked up to it, and a compass?  I believe once this example gets tied into the concepts of an electrical field and a magnetic field, I should have a clearer picture in my head about it.

In closing, I look forward to hearing back from everyone regarding this question.

Thank you

George
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Question by:GMartin

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A magnetic field is essentially what you get when you apply Special Relativity to moving electric fields.
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aadih earned 800 total points
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It's take too long to write an answer you want. You could read it an introductory Physics book.

But, here is a link with a video that answers your question in some detail.

http://www.diffen.com/difference/Electric_Field_vs_Magnetic_Field >

Let's know if the information there doesn't satisfy you. I'll provide another one...
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Assisted Solution

ozo earned 600 total points
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Technically, electric fields and magnetic fields are related by Maxwell's Equations:
http://en.wikipedia.org/wiki/Maxwell%27s_equations

I'm not sure that "made up of" is the best description of the relationship between electric fields and electrons.
For one thing, protons, positrons, muons, quarks, etc all have electric fields.
For another, the fields are not contained in the particles, although the field lines generally connect particles.
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The real short answer is:

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Del · B = 0 is is a statement that magnetic monopoles do not exist.
But although there have been no confirmed observations of magnetic monopoles, it has not been proven that they do not exist, and there are lattice systems that act like pairs of magnetic monopoles.
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aburr earned 600 total points
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None of the above really work for somebody without at least some physics background.
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One can say that a magnetic field is a field which can be detected by a compass. an electric field will have no affect on a compass.

An electric field is a little more difficult. It can move an electric charge. A magnetic field will have no affect on a charge (at rest). The difficulty is getting an isolated charge. You can do that by rubbing a balloon with wool. You can also put two parallel metal plates in an electric field and measure a voltage between them with a voltmeter.
There are a number of electric field meters available for sale on the internet, But some do not measure an electric field by itself.
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An electric field is created by a charge. A magnetic field is created by a moving charge.
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> an electric field will have no affect on a compass
unless they are in relative motion

> measure an electric field
Your eyes measure oscillating electromagnetic fields in a particular frequency range.

> An electric field is created by a charge. A magnetic field is created by a moving charge
Since the laws of motion are the laws of relativity, charges in different states of motion observe different electric fields.  This difference can be interpreted as a magnetic field.
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In a sense, you could say that Del · B = 0, i.e. that magnetic monopoles have not been observed to exist, is really the only basic difference between electric and magnetic fields.
If magnetic monopoles did exist, you would have nicely symmetrical equations, with moving electric monopole charges creating magnetic fields, and moving magnetic monopole charges creating electric fields.
I don't know of a fundamental reason why, if one exists and not the other, it should be the electric charges that exist and not magnetic monopoles rather than the other way around -- other than that since, in our ordinary experience, we observe one but not the other, our historical names "electric" and "magnetic" were developed based on that experience,
so if it were magnetic monopoles that we observed and not electric charges, we would have instead given electricity the name "magnetism" and given magnetism the name "electricity".
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None of the above really work for somebody without at least some physics background. ~ aburr.

If it could work (this way), who'd slog through Physics courses?
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ozo earned 600 total points
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Here's an explanation of how Special Relativity shows magnetic fields and electric fields to be the same thing from different frames of reference:
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If the density of the protons increase from the cat's perspective as the cat moves, then it would seem paradoxically that the number of protons increase in the wire. The faster the cat moves, the more protons are come into existence. But that might be explained away by saying that the length of the wire decreases in length so even though the proton density increases, the number stays the same.

But if the wire shortens, and the number of electrons remains the same, then its density increases also. So, don't the densities cancel out leaving a net 0 electrical charge.
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ozo earned 600 total points
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The number stays the same, the local density changes.

If we do not have a complete circuit, the electrons might pile up at the end of the wire,
but if the end of the wire is far away from the cat, the increased density far away would not cancel the decreased density nearby.
If we do have a complete circuit, then the electrons flowing the other way will increase in density, and if the currents flowing both ways are close to each other, then they can cancel.
But if the cat is closer to one wire than the other, then the effect of closer one can dominate.
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Author Comment

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Hello and Good Evening Everyone,

Thanks so much for the feedback given to this post.  To be perfectly honest, the true nature of my question was a bit more complicated than I had anticipated.  For example, when I first opened this question, I was naive and thought I could understand all angles of any feedback given to it without a physics background.  To my surprise, I was not able to fully do that.  However, the links provided did help some in getting a more tangiable understanding of the difference or differences between magnetic and electrical fields.  I still wish I had a physics background to better understand the distinction between the two using mathematical equations.  If I had such a background, I am confident I would had gotten so much more out of this post.

Once again, many thanks for the shared input.  At least I am walking away from this post knowing a little bit more than I did previously about this topic.  The online multimedia links did help a great deal in achieving this quest.

George
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