BACKGROUND:
Magnetism defies gravity. The
stronger the magnet, the less effect gravity has on the object. The
stronger the magnet, the more "pull" the magnet has toward
objects that are magnetic. This focuses on how the force of magnetism
can vary with different objects. Some substances seem not to be affected
by magnetism (non-magnetic) whiles others are attracted to it
(magnetic). Magnets made out of ALNICO (aluminum, nickel, and cobalt)
are much more powerful than steel magnets and are used in almost all
loudspeakers manufactured today. Cheap magnets are usually made from
iron or an iron alloy and are not permanent. They will lose their
magnetism over time. PROCEDURE:
- Review the third grade labs if
students find magnetism obscure. This lab will take the students a
little further in understanding the force of magnetism. Magnetism is a
very complex subject, and very important in our society. New advances
such as the MRI (magnetic resonance image) can help locate problems
inside the human body without an operation. Magnetism helps store images
through magnetic tapes. The uses are endless, and in the future
magnetism will probably solve many other problems.
- There are only three common
elements that are naturally magnetic: cobalt, nickel, and iron. Iron is
the weakest magnetic element. In 1935, gadolinium was also found to be
naturally magnetic. The objective of this lab is for students to explore
the mysteries of magnetism by doing several experiments. Use the lab
sheet to go over the steps with the students so they can work in groups.
- Experiment 1. Students should feel
the repulsion and attraction of the poles. North/north and south/south
repel while north/south attract. The notch on the magnet is North. North
is considered the positive side where the magnetism actually begins.
South is considered the negative side where the magnetic force reenters
the magnet.
- Experiment 2. Have students put a
piece of paper over the magnet. Lightly sprinkle a layer of iron filings
over the paper. Have students record the pattern. STRESS that students
should not to get iron filings on the magnet. These ALNICO magnets are
very strong and it is difficult to clean the magnet. Have students put
the filings back in the plastic bag at the end of the experiment.
- Experiment 3. Have students use
the magnet on these items to see if they attract or repel.
- Experiment 4. Discuss how magnetic
forces will go through most substances as long as they are thin enough
and the magnet is powerful enough.
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