What is a magnetic field? How were they formed?

1 Answer
Jun 13, 2016


I am not sure that my answer will satisfy you but...


A magnetic field is a region of space where, in every point, is present a magnetic force odf the type:
where #vecB# is our magnetic field (vector).

Here you can see a similarity with Electric Field where you have:

The difference is that the first has the velocity term in it!

We can resume all saying that:
A charge produces around itself an Electric Field #vecE#; if it moves it will also produce a Magnetic Field #vecB#. Both fields will be sensed by the presence of a force.

We can summarize mathematically by writing (for a charge #q#):
If the charge is at rest it is ok you get only a E field...if it also moves we add the Magnetic one!

Basically, every time you have a moving charge you have the formation of a magnetic field; for example:
1) around a wire carrying electricity;
2) in a magnetic material; this time caused by the electrons "moving" around in the atoms;
3) in and around a solenoid carrying a current (as in a transformer).

Hope it helps!