Magnetic Field Lines Crossing
Why is it that magnetic field lines do
not cross each other?
Magnetic field lines indicate the direction of the magnetic
field, which is always tangent to a field line. If the lines
crossed, the magnetic field would be pointing in two directions
at the point of crossing. Apart from being logically unpleasant,
it would mean that the magnetic force on a charged particle
passing through that point, which must be perpendicular to the
magnetic field, would be in two different directions at the same
The same arguments work for electric field lines. It's easier to
see there, since the electric force on a charged particle is in
the direction of the electric field.
Best, Dick Plano, Professor of Physics emeritus, Rutgers
A magnetic field can only point in one direction at a time. The direction
of the field line at a location is also the direction of the magnetic field
at that same place. If the field lines crossed at one location, the
magnetic field would have two different directions at one location. It
would point two different ways at once.
Dr. Ken Mellendorf
Illinois Central College
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Update: June 2012