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magnetic field

A magnetic field is generated when electric charge carriers such as electrons move through space or within an electrical conductor. The geometric shapes of the magnetic flux lines produced by moving charge carriers (electric current) are similar to the shapes of the flux lines in an electrostatic field. But there are differences in the ways electrostatic and magnetic fields interact with the environment.

Electrostatic flux is impeded or blocked by metallic objects. Magnetic flux passes through most metals with little or no effect, with certain exceptions, notably iron and nickel. These two metals, and alloys and mixtures containing them, are known as ferromagnetic materials because they concentrate magnetic lines of flux. An electromagnet provides a good example. An air-core coil carrying direct current produces a magnetic field. If an iron core is substituted for the air core in a given coil, the intensity of the magnetic field is greatly increased in the immediate vicinity of the coil. If the coil has many turns and carries a large current, and if the core material has exceptional ferromagnetic properties, the flux density near the ends of the core (the poles of the magnet) can be such that the electromagnet can be used to pick up and move cars.

When charge carriers are accelerated (as opposed to moving at constant velocity), a fluctuating magnetic field is produced. This generates a fluctuating electric field, which in turn produces another varying magnetic field. The result is a "leapfrog" effect, in which both fields can propagate over vast distances through space. Such a synergistic field is known as an electromagnetic field. This is the phenomenon that makes wireless communications and broadcasting possible.

This was last updated in September 2005

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awesome nice explanation

What, physically, is a magnetic or electric field? We Believe that there is a thing called atom made up of various bits and pieces. But those bit and pieces what are they physically? Is an electron a small ball of matter with an attached"Electric field"? Why then does a neutron not have such a field attached to it? What is that field physically made up of?

I would appreciate an answer to the question and not some round-about answer like the ones the internet is full of.

Or, is the case that we simply don't know? All we have is a mathematical construct derived from experiments, the solidity of which can be questioned?

Magnetic or electric field's are physically present but it cannot be seen, just like light raise coming from sun, secondly light raise are electromagnetic and electrostatic fields of extremely high frequency. 
No body has seen atom and revolving electrons around nucleus. At the beginning of 20th century (1900) no body was knowing how electricity is flowing through wire, scientists/ physicists were trying to find out the same. Around 1908 Albert Einstein mathematician and physicists read Vedas and told scientists that, similar to Sun and revolving planet model, is found in every smallest particle present on the earth. By looking into his statement, Rutherford and Neel Bohr started working on the model and finally Neel Bohr presented his atomic model and theory which we are using today in the form of periodic table. These are all imaginary but working perfectly in all spheres of life. When electron revolves around nucleus it produces magnetic and electric field, they are perpendicular to each other, so they never allow electrons to join with protons (opposite charge attracts) and thus electrons keep revolving around nucleus.
In neutron; protons and electrons are joined, as they are not revolving they cannot produce electric and magnetic field so it is electrically neutral and constitutes mass of an atom. Different number of electrons and protons forms an element, so property of one element is different from other.
This theory is well understood when a cell is connected to lamp; it glows, because current of free electrons revolving around atoms are forced to move around electric circuit. Flow of current can be sensed by magnetic compass. Similarly electric field is also created around circuit which is perpendicular to magnetic field.
Mathematical approach comes after the invention, Thomas Alva Edison has patented more than 1000 inventions, after that mathematicians applied different formulas and confirmed one formula which works correctly. I always tell my students mathematics is like a stick of a blind person, it tells what is present in the next step and not beyond that. Mathematics has no taste, smell, size, sense etc., we must know how it can be used. We can apply mathematics; only when we know in and out of the subject, other wise we go wrong in applying mathematics and say theory and practical are different.
Shri55, I think some elements atoms losing electrons having atom posi state could still be gaining back free electron hypothetically
Physics text only use hydrogen atom as electron mass.

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