 |
 |
Magnetism Basics
Name: Glenn
Status: student
Age: N/A
Location: N/A
Country: N/A
Date: N/A
Question:
While writing a unit on magnets, I was asked, well you
need to define magnetism and establish general understanding. The
facts are easy to list but what is magnetism? I wrote that it was a
form of energy that has specific properties and characteristics.
Well how accurate am I? Is it a form of energy or just a "force".
Replies:
Dear Glenn,
You have opened a great can of worms! Magnetism is a force that is
interrelated with electricity. I am assuming that you are looking
for explanations geared towards primary grades. May I recommend this website?
www.explainthatstuff.com/magnetism.html
It is a good website with basic information. You can look at your
benchmarks for primary grade science to determine how much you need
them to understand. It also lists a few books for further reading
at the end. One of the books has experiments that your kids might
enjoy doing. Let me know if this is enough to get you started. If
not, e-mail back with the primary benchmarks and I'll see if I can
help you out a little more.
Good Luck,
Martha Croll
Glenn
You can find your answer by going to http://www.google.com and searching for
"Magnetism".
There are a number of tutorial web pages written at all kinds of levels.
I get my best information from Wikipedia. It is an open source on-line
encyclopedia that is reviewed and edited by super experts in the field.
So when I "Google wiki" I get this:
http://en.wikipedia.org/wiki/Magnetism
This site describes magnetism this way:
"Magnetism is a category of behaviour of materials that respond at an atomic
or subatomic level to an applied magnetic field."
Yours is a complicated question. I do not think it is accurate to say that
magnetism is an energy. Energy is the "capacity to do work."
http://en.wikipedia.org/wiki/Energy
http://en.wikipedia.org/wiki/Work_(physics) defines work as a delta energy.
In the wiki.magnetism article, in the "Magnetic Fields and Forces" Section,
we see this:
"When a charged particle moves through a magnetic field B, it feels a force
F given by the cross product:
F = q (v X B)
where
q is the electric charge of the particle,
v is the velocity vector of the particle, and
B is the magnetic field.
Because this is a cross product, the force is perpendicular to both the
motion of the particle and the magnetic field. It follows that the magnetic
force does no work on the particle; it may change the direction of the
particle's movement, but it cannot cause it to speed up or slow down. The
magnitude of the force is
F = q v B sin(è),
where è is the angle between v and B."
Since magnetism cannot speed up or slow down a particle (0 delta energy),
the best we do to define magnetism is as a "category of behavior of
materials at an atomic or sub-atomic level..."
This site calls Magnetism a Force, but I cannot agree with that because a
bar magnet that displays the characteristics of magnetism does not exert a
force on anything if it is not in the magnetic field.
http://www.school-for-champions.com/science/magnetism.htm
Sincere regards,
Mike Stewart
You asked one of those questions that appears "simple" to ask but very
tough to answer in "simple" terms.
As you point out, you can list the facts of how it behaves, but absent from
that list is a simple explanation of "What it is."
I tried a search using the search term: "What is magnetism?" I too found a
lot about how it behaves but very little
about why it behaves the way it does. This problem is not unique to
"magnetism". There are a lot of such terms. For example:
gravity, electrical charge to name a couple. Science is good at explaining
"how things work" but not so good at "what it is."
I'll keep looking but I didn't want you to think you were being ignored. You
just asked a very hard question.
Not a simple answer but a good resource is the NASA website:
http://www-istp.gsfc.nasa.gov/Education/wmfield.html
Vince Calder
Hi Glenn
I think we must talk a bit in order to answer your question.
First the scientists discovered that there are 4 forces known that
sustain the universe called:
1. Gravity - This force acts between all mass in the universe and
has infinite range.
2. Electromagnetic This one occurs between electrically charged
particles. Electricity, magnetism are effects produced by this force
that also has infinite range.
3. The Strong Force - This force binds neutrons and protons together
in the cores of atoms and is a short range force.
4. Weak Force -Like the strong force, the weak force is also of short
ange. It is present inside the atom and it is related
with radioactivity, conversion and/or formation of different particles
inside the atom nucleus.
So when you speak of magnetism or electricity you rather say
“Electromagnetism” that results from the presence of an electromagnetic
force.
Electromagnetism, also called electromagnetic interaction, or
electromagnetic force is a long-range force involving the electric
and magnetic properties of elementary particles. Particles with the same
charge repel to each other and are attracted when have opposite charges.
It explains atomic structure (positive protons and negative electrons) and
the properties of light and other forms of electromagnetic radiation. Its
effects are easily observed such as light and heat.
Magnetism occurs when materials exert an attractive or repulsive force on
other materials, as a magnet.
Electricity is related to charges, and both electrons and protons carry a
charge. The amount of the charge is the same for each particle, but opposite
in sign. Electrons carry a negative charge while protons carry positive
charge. The protons are basically trapped inside the nucleus and can't
escape .As a result, it is moving electrons that are primarily responsible
for electricity.
Answering your question:
electromagnetism is a Force not Energy.
But is is also actually a secondary energy source, also referred to as an
energy carrier. That means that we can get electromagnetism from the
conversion of primary sources of energy, such as coal, nuclear, or solar
energy.
Thanks for asking NEWTON!
Mabel
Dr. Mabel Rodrigues
Glenn--
You are hitting at some interesting material. There is much confusion
between energy and force. Simply put, force is a push or pull, while
energy is a conserved quantity that flows when there is a change.
Contrary to what is commonly written about energy, there is only one kind of
energy: energy. It is all measured in joules. We describe energy by its
location. For example, if we lift a book from a table into the air, the
energy transferred from us to the gravitational field. We can describe
this by U=mgh. If the object is moving, we call it kinetic energy (energy
stored in the motion of the body) and is described by the equation K=(1/2)mv^2.
Force is not a conserved quantity. When the force is no longer applied, it is
not transferred anywhere else, it just ceases to exist. This never happens
with energy.
Magnetism is a field that can exert forces on objects. This, in turn, can
result in a transfer of energy into or out of the magnetic field.
There are many web sites that address or identify science misconceptions.
Here are a few:
http://www.darylscience.com/Misconceptions.htm
http://www.physicstutorials.org/index.php/home/mechanics/1d-kinematics/misconceptions
http://www.eskimo.com/~billb/miscon/opphys.html
http://phys.udallas.edu/C3P/Preconceptions.pdf
http://dese.mo.gov/divimprove/curriculum/science/SciMisconc11.05.pdf
http://homepage.mac.com/vtalsma/syllabi/2943/handouts/misconcept.html
There are many other sites in the Physics Education Research and Science
Education Research. Frankly, you may harbor some of these misconceptions.
I know I still harbor some. Teach the best you can while you learn about the
misconceptions and try to devise strategies to confront them. I know that I
have taught misconceptions, and I work diligently to uncover my own
misconceptions to better serve my students. I encourage you to keep on learning!
---Nathan A.Unterman
Click here to return to the Physics Archives
| |
Update: June 2012
|
|
