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Unit 11: Magnetism Page 14
Now, imagine what would happen A gravitational field, for example,
if the magnets inside the box did comes from a body of some sort.
all face the same way. If I stuck The larger the body the greater the
them all end to end and created a force. A planet, for example, is a
long string of magnets. Now the large body with a large
box would have a very powerful gravitational force. If another body
magnetic force, right? This is the gets within the gravitational field of
difference between an iron nail and the planet, it will be affected by the
a magnet. The nail has iron atoms force.
going all which ways, while the
magnet has iron atoms that are What creates the force?
fairly lined up. The more lined up What’s pulling or pushing?
the iron atoms are, the stronger
the magnetic force. Nobody knows! We just know that
it happens.
What’s a magnetic field?
Another thing about forces is that
Well, I can’t the farther something gets away
tell you. To be from the source, the less and less
honest, the force works on that object. A
nobody can. fancy term for this is the inverse
Magnetic square law. Something quite far
fields, from the Earth will feel no tug from
gravitational the Earth’s gravitational pull. If it
fields, electric fields are very gets closer it will feel a slight tug.
mysterious and at this point there Closer still, a stronger tug will be
are still lots of questions about felt. The closer something gets to
each one. the source of a field (gravitational,
magnetic or electric) the stronger
A field is an area around an the pull of the field force is. If
electrical, magnetic or gravitational you’re standing on top of the Sears
source that will create a force on Tower in Chicago you are actually
another electrical, magnetic or going to weigh less then if you’re
gravitational source that comes standing in the street.
within the reach of the field. (Now
you can see why there’s still so Weight depends on the pull of
much mystery about them!) gravity. The farther you are from
the Earth, the less gravity pulls on
you and the less you will weigh!
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