Let's have some fun using a magnetic field demonstrator to do a cool science experiment. We will
demonstrate the magnetic fields that exist inside the earth! We will see how the earths magnetic
shield or magnetosphere looks and explore what it does.
- Magnetic Field Demonstrator Kit
- Cow Magnet (included)
- Iron Filings (included
Watch The Magnetic Field Demonstrator Video:
Process For The Magnetic Field Demonstrator Science Experiment
1) Insert the cow bar magnet into the center of the magnetic field demonstrator.
2) Spin it in a circle or shake it up.
3) The iron filings will attract to the magnet.
4) Watch as the magnetic lines form inside the field demonstrator.
The Science Behind The Magnetic Field Demonstrator Experiment
The Earth's magnetic field is similar to that of a bar magnet tilted 11 degrees from the spin axis of the
Earth. The magnetic field of earth provides a shield (called the megnetosphere) from solar winds
and radiation. Without it the earth would be barren and too hot for life. The problem with that picture is
that the Curie temperature of iron is about 770 C . The Earth's core is hotter than that and therefore
not magnetic. So how did the Earth get its magnetic field?
The north pole of a compass needle is a magnetic north pole. It is attracted to the geographic North
Pole, which is a magnetic south pole (opposite magnetic poles attract).
Magnetic fields surround electric currents, so we surmise that circulating electic currents in the
Earth's molten metalic core are the origin of the magnetic field. A current loop gives a field similar to
that of the earth. The magnetic field magnitude measured at the surface of the Earth is about half a
Gauss and dips toward the Earth in the northern hemisphere. The magnitude varies over the surface
of the Earth in the range 0.3 to 0.6 Gauss.
The Earth's magnetic field is attributed to a dynamo effect of circulating electric current, but it is not
constant in direction. Rock specimens of different age in similar locations have different directions of
permanent magnetization. Evidence for 171 magnetic field reversals during the past 71 million years
has been reported.
Although the details of the dynamo effect are not known in detail, the rotation of the Earth plays a part
in generating the currents which are presumed to be the source of the magnetic field. Mariner 2 found
that Venus does not have such a magnetic field although its core iron content must be similar to that
of the Earth. Venus's rotation period of 243 Earth days is just too slow to produce the dynamo effect.
Interaction of the terrestrial magnetic field with particles from the solar wind sets up the conditions for
the aurora phenomena near the poles. The north pole of a compass needle is a magnetic north pole.
It is attracted to the geographic North Pole, which is a magnetic south pole (opposite magnetic poles
Reference source: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magearth.html
The magnetosphere shields (Above) the surface of the Earth from the charged particles of the solar
wind and is generated by electric currents located in many different parts of the Earth. It is
compressed on the day (Sun) side due to the force of the arriving particles, and extended on the night
Simulation of the interaction between Earth's magnetic field and the interplanetary magnetic field.
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