MAGNETIC FIELDS BASICS
Polarity
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In much of the popular writing on magnetic fields
used in therapy, there is much discussion about
polarity. This concept is taken from the convention
used to describe the Earth's poles - North and
South. There are actually two types of poles on the
Earth. Magnetic and geographic. The magnetic poles
are not physically situated in the same place as the
geographic poles. There's confusion in the
conventions used to describe magnetic poles.
Normally, when someone is talking about the North
Pole, meaning the one to which the compass points
north, they are really referring to the
North-seeking pole. That means the actual "North
Pole" geographically is a magnetic South Pole. The
compass needle's North Pole is attracted to the
magnetic South Pole. To avoid confusion, many people
now use the term, the North seeking pole to be
clear. |
To avoid
confusion, and to standardize magnetic fields, measurement
instrumentation, scientists and engineers use positive and
negative instead to describe magnetic poles. The positive pole
is considered the North-seeking pole, and the negative pole is
considered the South-seeking pole.
Unlike
electricity, magnetic fields do not have charge. This means the
terms positive and negative do not carry the same meaning for
magnetic fields as they do electrical fields.
From
a physics perspective, magnetic poles do not have specific
actions, stronger/weaker or energizing/relaxing. There is no
good, repeatable scientific research to support a separate
action for each pole. The issue of polarity is primarily focused
on static magnetic fields, that is, permanent magnets. This
means that permanent magnets may be applied to the body,
regardless of polarity without significant concern for harm.
Strong statements are made in the popular literature on polarity
and have led people to be frantic about "getting it
right" but until there is strong objective scientific
evidence to support these claims, I remain unconvinced about the
importance of proper polarity placements.
In
addition, even if there is some basis for polarity differences,
there are other problems in this concept. Every magnet's fields
bend over the sides and "reverse polarity." This means
that placing the magnets over the body will still provide the
body with a bipolar exposure. Only if the magnetic system is
large enough to contain a whole person, could this theory be
tested. Small structures such as seeds, small plants or small
animals may be placed wholly on a magnet or in a uni-directional
DC electromagnetic field for testing purposes. So far, the
results are not consistent or reproduced by other scientists.
Individual experience is subject to an expectational bias, which
can only be avoided by properly controlled experiments.
Humans
are continually exposed to both polarities in any event. Most of
the research using time-varied magnetic fields, pays no regard
to polarity for the most part. Alternating current, of course,
has alternating polarities. Pulsed magnetic fields can be
designed to be positive and/or negative. No systematic
differences have been discovered in one polarity versus another
for time-varied fields either.
In magnetic
systems that use alternating pole arrangements, that is, multi-polar
arrays, a large amount of cancellation occurs, substantially
reducing the field strength applied below the skin surface.
Field strength therefore becomes important in getting strong
effects. This does not mean effects are not possible, they just
may take longer to achieve, if they don't happen quickly
otherwise. See the levels of pathology in the treatment section
to understand how this works.
