Magnetic Field

A magnetic field is the domain in between two magnetic objects, in which they begin to magnetically influence each other. The direction of the magnetic field at any point could analogically be determined by the direction of a compass needle at that point. Magnetic fields are generated by steady currents. The following important properties define a magnetic field

Properties of Magnetic Fields

1. The direction of the magnetic field due to a current is defined by the right-hand rule as shown here.
2. The lines of a magnetic field (the lines to which a magnet is tangential) are always closed lines.

Magnetic Fields generated by an Electric Current

If an electric current flows through a medium it also induces a magnetic field, which is shown in the figure by the current $I$ flowing in a circular path. Magnets in the magnetic field will orient themselves parallel to the shape of the current’s path and direction. Thus follows by the right-hand rule:

“if the thumb of the right-hand shows the direction of current, the curled fingers show the direction of the magnetic field.”

Magnetic Force

The magnetic force $F\_m$ in its relation to electric charge $q$, charge velocity $v$, and the magnetic flux density $B$, is described by the Lorentz force equation

$$F\_m=qv\times B$$

This equation applies to moving charges in magnetic fields (Coloumb force for charges in electric fields - the Lorentz-Coloumb force equation unifying both)