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TRANSCRIPT
Subject Matter Research- MagnetsGrey CohortAndrea BalarezoKristin KirkpatrickLindsi CiuffetelliMaroon CohortKatherine RountreeMelissa KrollKevin Swartz
Big Ideas
Permanent magnets
Permanent magnets are those that retain a certain level of magnetism once
they are magnetized. They are generally made of ferromagnetic material, which
consists of atoms and molecules that each have a magnetic field and are positioned
to reinforce each other (Jezek, 2006). Permanent magnets are the kind that we are
most familiar with, like the kind that people use to hang items on their refrigerators.
There are four different types of permanent magnets based on their
composition and each type varies in how easily they can be demagnetized, how
strong they are, and how their strength changes due to temperature. Rare earth
magnets, Neodymium Iron Boron and Samarium Cobalt, are very strong and very
difficult to demagnatize. Alnico is a type of permanent magnet that is made of
Aluminum, Nickel, and Cobalt and is easily demagnetized, but least affected by
temperature. The current most popular type of permanent magnets is Ceramic or
Ferrite, made of Strontium-Iron, which is the weakest type of magnet, and its
magnetic strength varies with temperature (What are permanent magnets made of?,
2000).
Permanent magnets can be demagnetized by high heat, contact with another
magnet, or hammering, which loosens the magnet’s atoms (Jezek, 2006).
Induced Magnets
Induced magnets, or temporary magnets, are ones that only exhibit magnetic
properties when they are inside another magnetic field (“How magnets work,”
2006). One may easily observe an induced magnet after attaching a regular paper
clip to a permanent magnet. If you make a chain by touching this paper clip to
another, it will “magically” lift it up. This is because the first paper clip is an induced
magnet; when you remove it from the permanent magnet, it no longer acts this way.
People may also make an induced magnet by repeatedly stroking a magnetic
object, from tip to tip, along one part of the magnet. This will force the molecules in
the object to temporarily align themselves with the poles, thus creating an induced
magnet.
Electromagnets are another example of induced, or temporary, magnets.
These are created by winding copper wire into tight coils around a piece of soft iron
and passing an electrical current through it. When the current is flowing through
the wire, the iron is magnetized, creating an electromagnet. When the current stops
flowing, the iron is no longer magnetized (“How magnets work,” 2006).
Electromagnets are used in most electrical household items, including washing
machines, computers, and stereo systems.
Magnetic Force
A magnet is an object that has a magnetic field surrounding it. Every magnet
will have at least two poles—a North pole and a South pole. If a magnet is cut in
half, it will continue to have two poles. It has not been proven possible to have a
magnet without two poles, so no matter how small a magnet gets, it will still have
both. Typically, magnetic field lines are considered to leave from the North pole and
enter through the South Pole (Hoadley, 1998). The magnetic field that surrounds
every magnet is created by the lines of force going between the North and South
poles (Flaherty, 1999). Magnets attract ferrous objects like pieces of iron, steel,
nickel, and cobalt. Magnets do not attract all metals, as is the common
misconception. A magnet’s pole will also attract another magnet’s unlike pole. For
example, the North pole of one magnet will attract the South pole of another. On the
other hand, repulsion will occur when two like poles of magnets are put close
together (Jezek, 2006).
Magnet Experiments
1) Magnetic Force- attraction and repulsion of poles
This experiment, found in Magnetism by Penny Norman, is designed for
students to discover how magnets attract and repel other magnets based on poles
(2008, p.8). Students would be given a pencil or straw, and five circular magnets
that have red painted on its north pole and white painted on its south pole. They
would then be told to put the straw between the hole of one of the magnets, with the
red side facing towards the ceiling. Placing one magnet down the straw with the
white side facing up, watch how the second magnet seems to “float” on the straw.
The students would be allowed to explore how to make other magnets float or stick
to each other, and asked to explain why they think this happens. This is a fun way
for students to discover the polarity of magnets and the force within them.
Here is an example of the experiment in motion:
2) What is magnetic?
Through a “discovery bottle,” detailed in Discovery Bottle by Kay Kent,
students are able to see what a magnet sticks to and what it does not (2002, p.17).
We would put various magnetic objects (such as paper clips, scissors, a brass clasp)
and non-magnetic objects (such as a plastic badge, a penny, aluminum foil) into an
empty two-liter bottle. The bottle would then be filled with paper shreds so the
objects are hidden from students view. Using a magnet rod, students would run it
up and down the outside of the bottle to discover what items stick to the magnet
through the bottle. They would then use sheets to draw which objects they saw
before the bottles were emptied.
We did not have a plastic bottle, so we put the items onto a table and went “fishing;”
however, here is how it would look in the bottle, shown on the worksheet:
3) Does the size of the magnet determine its strength?
The book, More Picture-Perfect Science Lessons, by Ansberry and Morgan
describes an experiment for students to discover the strength of a magnet (2007,
p.127). This experiment requires magnets of several different sizes and shapes. We
put twenty paper clips into a paper bag, and tied a string to two different shapes of
magnets, circular and bar shaped. We then “went fishing” into the bag to see how
many paper clips each magnet would pick up. Students could then make a graph of
how many each type of magnet picked up for a visual representation of the different
strengths of magnets.
Here is the experiment in motion:
Scientific MisconceptionsA scientific misconception is an idea or belief that a student has about science that
is inconsistent with the actual scientific idea. Often times, the student doesn’t even know
that they hold these misconceptions and struggle with releasing them. Misconceptions are
formed a number of ways, which include incorrect information from the parents, by word
of mouth, and by the students trying to make sense of an idea with limited experience or
understanding. Misconceptions about science are very common; however, they can be
used to help the students build on their own understanding.
Common misconceptions students hold about magnets and magnetism
A misconception about magnets is that magnets only attract and do not repel.
Several of the students might think that magnets will be attracted to everything, including all metals.
Some students think that magnets are only attracted to iron and that all magnets are made of iron.
It is thought by some that magnets are only attracted to metal objects that are silver.
Students have a hard time with the concept that magnetic fields are not two-dimensional like what they see in their textbook. In fact, magnetic fields are three-dimensional and surround the object.
Students think that only metal magnets have a magnetic field.
It is common for students to think that the larger the magnet the stronger the magnet pull is.
Some students believe that magnetism is magic.
Many students think that magnetism cannot go through objects and that things that are insulators could block magnetism.
A very common misconception about magnetism, even with adults, is that the geographic and the magnetic poles of the earth are in the same place.
Students commonly refer to the poles of a compass as north and south and believe that the north pole of the compass points to the north pole of the earth, when in fact the south pole of the magnets points north due to its attraction.
Diigo Links Posted by Lindsi Ciuffetelli
Bibliography
Ansberry, K., & Morgan, E. (2007). More Picture-Perfect Science Lessons. National Science Teachers Association.
Bentley, M. (2003, December 31). Earth loses its magnetism. BBC News. Retrieved September 27, 2008, from http://news.bbc.co.uk/2/hi/science/nature/3359555.stm
Branley, F. (1996). What makes a magnet? New York: HarperCollins Publishers.
Catherall, E. (1990). Magnets. Austin, TX: Steck Vaughn.
Chang, K. (2008, July 25). Scientist Find Trigger for Northern Lights. The New York Times. Retrieved from http://www.nytimes.com
Discello, C. Magnets. Retrieved September 29, 2008, from Lesson Plans Page Web site: http://www.lessonplanspage.com/ScienceMagnets-PolesStrengthAttractedObjects2.htm
Flaherty, M. (1999). Magnetism and Magnets. Brookfield, Conn: Copper Beech Books.
Hapkiewicz, A (1992). Science Misconceptions. Retrieved September 29, 2008, Web site: http://www.cedu.niu.edu/scied/resources/sciencemisconceptions.htm
Hoadley, R. (1998, June). Cool Experiments with Magnets. Retrieved September 29, 2008, from Magnet Man Web site: http://www.coolmagnetman.com/magindex.htm
How Magnets Work (2006). Retrieved September 25, 2008, from http://www.howmagnetswork.com/
How Magnets Work (2008). Retrieved September 26, 2008, from http://science.howstuffworks.com/magnet.htm
Kent, K. (2002). Discovery Bottle. Aims Education Foundation.
Kids Konnect, Magnets. Retrieved September 29, 2008, from Kids Konnect Web site: http://www.kidskonnect.com/content/view/90/27/
Krensky, S. (1992). All about magnets. New York: Scholastic.
Jezek, G. (2006). How magnets work. Retrieved September 29, 2008, from How Magnets Work Web site: http://www.howmagnetswork.com/
Leyden, M (2008, September). Science can be Attractive. Retrieved September 30, 2008, from Findarticles.com Web site: http://findarticles.com/p/articles/mi_qa3666/is_199404?pnum=3&opg=n8715055&tag=artBody;col1
Magnetic Resonance Imaging (MRI). (2004, May 20). . Retrieved September 28, 2008, from http://www.bbc.co.uk/dna/h2g2/A2263493
Norman, P. (2008). Magnetism. El Sobrante, CA: Norman and Globus, Inc.
Ray, C.C. (2008, February 19). Q and A: Magnetic Personalities. The New York Times. Retrieved from http://www.nytimes.com
Sweetland, R Electricity and Magnetism. Retrieved September 29, 2008, Web site: http://www.huntel.net/rsweetland/science/misconceptions/electMagnet.html
What are permanent magnets made of? (2000). Retrieved September 29, 2008, from http://www.magnetsales.com/Design/FAQs_frames/FAQs_2.htm