1. Magnetism
Pg. 76

2. Magnetism
Pg. 76
EQ: What are the properties of magnets and the characteristics of a magnetic field?
LO: We will investigate what it means for an object to be magnetic.
CT: I will review my notes and demonstrate my comprehension of the concept by completing the overview.

3. Magnetism

4. Magnets have been known for centuries
Magnets have been known for centuries. The Chinese and Greeks knew about the “magical” properties of magnets. The ancient Greeks used a stone substance called “magnetite.” They discovered that the stone always pointed in the same direction. Later, stones of magnetite called “lodestones” were used in navigation.

5. What is Magnetism?
Magnetism is the invisible force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons.

6. What makes a magnet a magnet?
Hi! We’re e- (electrons)!!! We usually speed around the outside of the nucleus
In these atoms, each e- is going its own way
Wagon does not move; forces are not lined up
Wagon moves; forces are lined up
But in a magnet or a metal, we can line up to become magnetic
Lined up atoms/ electrons=Domain

7. What makes a magnet a magnet?
Atoms themselves have magnetic properties due
to the spin of the atom’s electrons.
Groups of atoms join so that their magnetic fields
are all going in the same direction
These areas of atoms are called “domains”

8. What makes a magnet a magnet?
When an unmagnetized substance is placed in a magnetic
field, the substance can become magnetized.
This happens when the spinning electrons line up in the
same direction.
What makes a magnet a magnet?

9. What makes a magnet a magnet?
An unmagnetized substance looks like
this…
What makes a magnet a magnet?

10. This makes a magnet a magnet
While a magnetized substance looks
like this… Aligned Domains
This makes a magnet a magnet

11. How to break a magnet: 1. Drop it 2. Heat it
This causes the domains to become random again!

12. MAGNETS Materials whose atoms can be aligned
Elements that can be magnetic
Fe: Iron soft iron loses magnetism easily
Co: Cobalt used to harden tools
Ni: Nickel used to make jewelry
Other magnets:
Compass
Earth

13. MAGNETS Properties Have domain (lined up atoms)
Have polarity (North and South)
Cannot have only 1 pole. Come in pairs *** magnetic poles cannot be isolated***
Like poles repel; Opposite poles attract

14. Poles of a magnet always
Come in pairs!

15. If you cut a magnet in half,
you get 2 magnets!

16. MAGNETIC FIELDS
An area where the force exists; area where force is felt
Magnetic field lines
Leaves north pole & enters south pole
Lines closer together = stronger field
NOTICE
Strongest at the poles

17. The Earth is a magnet:
Sometimes, the Earth’s magnetic poles flip. This happens every half-million years or so.

18. We use the Earth’s magnetic field to find direction.
Sketch the earth with its poles and circle the compass which will be most affected by the earth’s poles?
The needle of a compass always points toward the magnetic north pole.
We call this direction “North” (remember, opposites attract)

19. The sun has a magnetic field, too
The sun has a magnetic field, too. It extends far above the sun’s surface.
Other planets in the solar system also have these magnetic fields

20. Magnetic Force https://www.youtube.com/watch?v=VHhk8Atatp0

21. Earth’s Magnetic Force

22. The Earth’s magnetic field extends far into space
The Earth’s magnetic field extends far into space. It is called the “magnetosphere.”
When the magnetic particles from the sun, called “solar wind”, strike this magnetosphere, we see a phenomenon called…

23. The Aurora Borealis in the Northern Hemisphere
And the Aurora Australis in the Southern Hemisphere