1. T.O.C Magnetism is a Force that acts at a Distance
Chapter 3; Lesson 3.1
T.O.C
Magnetism is a Force that
acts at a Distance

2. Magnets attract & repel other Magnets
Magnets(w.w) object that attracts certain other materials, like iron & steel
Magnetism(w.w) force exerted by a magnet
Magnets do not have to touch objects to exert a force on it. (Like gravity/static electricity)
Ex: refrigerator door
Magnetism is the result of a moving electric charge.

3. What is
happening
in each photo?

4. Continued….
The force of magnetism is not evenly distributed throughout a magnet.
Magnetic Poles(w.w) the parts of a magnet where the magnetism is the strongest.
Every magnet has a north-seeking pole. The other is the south pole.
Like electricity; opposite poles attract & like poles repulse
Magnetic Field(w.w) region around a magnet in which the magnet exerts force.
The arrangement of magnetic field lines depends on the shape of the magnet.
Magnetic field lines always start at N. & end at S.
*Iron filings/magnetic field DEMO*

5. Some Materials are Magnetic
Inside nonmagnetic/magnetic materials:
In materials that are not magnetic, like wood, the magnetic fields of the atoms are weak & point in different directions cancelling out the magnetic field.
In materials that are magnetic, such as iron, magnetic fields of a group of atoms align & point in the same direction.
Magnetic Domain(w.w) group of atoms whose magnetic fields are aligned.
A magnet is a material in which the magnetic domains are all aligned.
*Lab- Is it Magnetic?*

6. Temporary v. Permanent Magnets
If you bring a magnet near a paperclip containing iron, the magnet pulls the paperclip towards it. This aligns the paperclip atoms & creates a magnetic field. OBSERVE *demo*
Remove the magnet → the paperclip chain dissolves
The paperclip chain is a TEMPORARY magnet.
A permanent magnet can be created by placing magnetic materials inside a strong magnetic field, or by repeatedly stroking a piece of magnetic material in the same direction w/ a strong magnet.
*Demo- Permanent magnet*
1- find North on compass. Align iron nail.
2- heat iron nail. Remove from heat keeping aligned.
3- stroke with strong magnet in only one direction.
4- when the iron nail cools, it will be magnetized.

7. Earth is a Magnet
An easy way to see this is w/ a compass. They will always point N.
The magnetic field of Earth acts like a large bar magnet that runs thru Earth’s axis.
The source of Earth’s magnetic field is the motion of its core, which is mostly composed of iron & nickel charged particles.
Earth’s magnetic field affects all magnetic materials around you!
Earth’s magnetic poles can reverse! Has happened about 400 times.
Evidence: shown in layers of rocks on the ocean floor. Iron in minerals line up w/ the poles.
*Lab- create a compass*

8. Magnetism & the Atmosphere
A constant stream of charged particles is released by reaction inside the Sun.
These particles could damage living cells if they reached Earth’s surface.
Earth’s magnetic field deflects this flow of charged particles.
Many of these particles are deflected toward the magnetic poles of Earth. As they approach, the particles react w/ Oxygen & Nitrogen in Earth’s atmosphere.
These reactions can be seen at night as vast moving sheets of color that can fill the whole sky. These are the Northern or Southern Lights.

9. 3.1 Review Q’s 10 pts
Why are some materials magnetic & not others? (2 pts)
What force causes magnets to attract/repel one another? (2 pts)
What is the source of Earth’s magnetic field? (2 pts)
Where is the magnetic field of a magnet the strongest? (2 pts)
How can the maglev train operate without touching the tracks? (2 pts)