Hi,

I would like to know what the difference between a magnetic field is and an electromagnetic field produced by a wire a coil?
Sometimes they talk about magnetic field there and sometimes they call it Electromagnetic.
I think it is an electromagnetic field at any case, so why they do so?

 

Electromagnetic field have crossed electric & magnetic field.Both the fields are perpendicular to each other & to the direction in which they are propagating.EM basically replicates itself each cycle & hence the wave propagates.

All these are not required to be met in case of magnetic field.

 

When ac current passes through a conductor, there is a magnetic field that exists around the conductor and there is an electric field that exists along the length of the conductor. If energy leaves the conductor and radiates away, never to return, the field contains both electric and magnetic parts that cannot be separated. This is a radiating, or electromagnetic field.

So, in the industry, if we say electromagnetic field, we are referring to a radiating field, which describes energy is passing through space (power is actually flowing through space). The magnetic field that exists around a conductor and that is not part of the radiating field is storing energy, but that energy is returned to the conductor at some point. We call this the Near magnetic field or just the magnetic field. Similarly the near electric field does not radiate and only stores energy to be returned to the conductor.

The near field and far field of the magnetic energy are not really separate, they are parts of the same overall magnetic field. We just call them different things to distinguish between the energy that does not radiate away and the energy that does. Same with electric.

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RadioRon

 

Can there really be a magnetic field without an electric field?
I mean, doesnt electric feild always exist when current flows?

 

A permanent magnet has no electric field. It is a static magnetic field.

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We never have time to do it right; but we always have time to do it over.

 

The only electric field around a wire is due to its voltage, not its current. A coil made with superconducing wire can carry a current with no voltage, thus it will have a magnetic field with no electric field, similar to a permanent magnet.

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Carl
Curmudgeon Elektroniker

 

When AC current flows then there must be both. However, in some cases there may be high magnetic field and low electric field, while in other cases there may be high electric field and low magnetic field magnitudes. It depends on several factors, including the shape/direction of current flow and resistance.

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RadioRon

 

The magnetic field is however in place because of a synergy of electron orbits in the material that makes up the permanent magnet. I don't understand it very well. Magnetism has always been a black science to me, something I should read up more on.

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Yea I do know that Voltage produces Electric field and current produces Magnetic field.
But If you make a magnet by a nail and several wounds of wires then what do you call it? an electric magnet or an Electromagnet or..? and which one is more correct to calling?

Yea I ever had a big problem to understand the ""domain theory" of a permanent magnet too.