Magnets

Pre-Assessment (Know)
1. What are some "real life" applications of magnetism?
Electromagnetism uses the push and pull of magnets to run things...right? Roller coasters?

2. What experiences have you had with magnets in your life?
I use magnets to pick up tiny metal things (needles, nails). I play with magnets.

3. What ideas do you have about the science of magnets?
Only some metals are magnetic, right? Nickel, iron, and lead? cobalt
Magnets have poles. Opposite poles attract. Same poles "push" repel apart
Compasses use magnetic fields. Birds use magnets to know north and south...

That's all I got.

Post-Activity (Learned)


How do the results compare with your predictions? Explain.
I predicted that metallic objects would "channel" the magnetic force. :( And non-metallic items would break field. BUT I know that magnets can "go through" paper, etc. Strong enough magnets can go through your hand. So. I basically guessed.

National Science Education Standards:
Physical Science: Content Standard B Light, Heat, Electricity, & Magnetism
Benchmark: Magnets attract and repel each other and certain kinds of other materials.

Research:

(Source: www.howmagnetswork.com )

History
Magnets were discovered/talked about by the ancient Greeks and Chinese. Greeks thought that magnets or "lodestones" had magical capabilities that attracted iron. They believed that there were islands entirely made of magnetite that pulled in ships by their iron nails; this was one of the explanations for ships lost at sea.

In 1269, Perigrinus wrote the first scientific report of magnetism, trying to understand science over superstition. In 1600, Gilbert figured out that the earth was a giant magnet and that the north and south poles are magnetic poles just like a small magnet. Since simple compasses already existed, this explained why they worked.

In 1820, Oersted discovered that there is a relationship between magnetism and electricity by putting a wire with an electric current near a magnetic compass. The electric current caused a "deflection" of the compass needle. We now know that this is because an electric current (or movement of a charged particle) creates a magnetic field also.

In 1862, Maxwell established the foundation of today's theories of electromagnetism (which I have yet to understand), thirty years before the electron was discovered.

Earth's Magnetic Fields
The geographic "North Pole" of the earth is actually the south pole of earth as a magnet. It is called the north pole because it attracts the north pole of other magnets (opposites attract). Thus the geographic "South Pole" is actually the magnetic north pole of the earth.

Magnets do not actually point perfectly north/south because the magnetic poles are not perfectly lined up with our geographic locations of the poles. This is because the axis of the magnetic field is different than the earth's axis.

Cause: It is now believed that the earth is a giant electromagnet because of a flowing current in the earth's core.

Electromagnetism 101
The "magnetic effect of a current" just means that an electrical current has a magnetic field. (Oersted, 1820) This magnetic effect of a current is called electromagnetism, as oppose to "plain" magnetism of a rock. :)