- Field line
A field line is a
locus that is defined by avector field and a starting location within the field. A vector field defines a direction at all points in space; a field line may be constructed by tracing a path in the direction of the vector field. More precisely, thetangent line to the path at each point is required to be parallel to the vector field at that point.Field lines are useful for visualizing vector fields, which consist of a separate individual vector for every location in space. If the vector field describes a
velocity field, then the field lines followstream line s in the flow. Perhaps the most familiar example of a vector field described by field lines is themagnetic field , which is often depicted using field lines emanating from amagnet .A complete description of the
geometry of all the field lines of a vector field is sufficient to completely specify the "direction" of the vector field everywhere. In order to also depict the "magnitude", a selection of field lines is drawn such that the density of field lines (number of field lines per unit area) at any location is proportional to the magnitude of the vector field at that point.Field lines can be used to trace familiar quantities from
vector calculus :divergence may be seen as a net geometric divergence of field lines away from (or convergence toward) a small region, and the curl may be seen as a helical shape of field lines.While field lines are a "mere" mathematical construction, in some circumstance they take on physical significance. In the context of
plasma physics ,electron s orion s that happen to be on the same field line interact strongly, while particles on different field lines in general do not interact.References
*cite book | author=Griffiths, David J. | title=Introduction to Electrodynamics (3rd ed.) | publisher=Prentice Hall | year=1998 | id=ISBN 0-13-805326-X | page=pages 65-67 and 232
See also
*
Force field (physics)
*External ray — field lines of Douady-Hubbard potential ofMandelbrot set or filled-in Julia sets
*Line of force
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