1. Magnet Notes!

2. What is a Magnet?
A magnet is any material that attracts iron or things made of iron.

3. History of Magnets
Over 2,000 years ago, Greeks discovered a mineral that attracted things made of iron
Found in a part of Turkey called Magnesia, so they called it Magnetite

4. Magnetic Properties
Magnetic Poles
Magnetic Forces
Magnetic Fields

5. The force of attraction or repulsion magnets exert on each other
Properties of Magnets
Magnetic Poles
Every magnet has a north and south pole-points on a magnet that have opposite magnetic qualities
Magnetic Forces
The force of attraction or repulsion magnets exert on each other

6. Attraction/Repulsion
Examples of Repulsion:
Example of Attraction:

7. The region around a magnet in which magnetic forces can act.
Magnetic fields
The region around a magnet in which magnetic forces can act.

8. What are the atoms inside of a magnet doing?
As negatively charged electrons move around, they make, or induce, a magnetic field.
In most material the magnetic field of individual atoms cancel each other.
In some materials the north and south poles line up in a domain (place where groups of atoms are found).
If most of the domains in an object align they can combine to make an entire object magnetic.

9. What does the inside of a magnet look like?
Inside a non-magnetic object
Inside a magnetic object

10. Can magnets be demagnetized?
When a magnet’s domains move, the magnet is demagnetized and loses its magnetic properties.
This can be done by:
Dropping a magnet
Hitting it too hard
Putting a magnet in a strong magnetic field that is opposite to its own
Increasing the magnet’s temperature-with a higher temperature, atoms vibrate faster and the atoms in the domains may no longer line up

11. Making a magnet
To make a magnet out of something made of iron, cobalt, or nickel:
Line up the domains by rubbing the object with one pole of a magnet
Domains in the object will line up with the magnetic field of the magnet
This is why a magnet can pick up an unmagnetized object like paper clips
When a magnet is close to the paper clip, some of the domains in the paper clip line up with the field of the magnet.
When the magnet is removed, the paper clip’s domains become scrambled again.

12. Kinds of magnets Temporary Magnets Permanent Magnets
Made from materials that are easy to magnetize, but lose their magnetism easily.
Soft iron is iron that has not been mixed with any other materials and can be made into temporary magnets
The paper clip and nail in the mini-lab were temporary magnets.
Difficult to magnetize and keep their magnetic properties longer than temporary magnets.
Some permanent magnets are made with alnico-an alloy made up of aluminum, nickel, cobalt, and iron.

13. What would happen if you cut a magnet?
Would you end up with one north pole and one south pole? NO
When you cut a magnet, you get two magnets, each with its own north and south pole.
Why?
A magnet has poles because its domains are lined up, and each domain is like a very tiny magnet with a north and south pole, so even the smallest pieces of a magnet have a north and south pole.

14. Magnetic Field notes

15. Magnetic fields
Region around a magnet in which magnetic forces can act
Shape is shown with lines drawn from the north pole of the magnet to the south pole, called magnetic field lines
The closer together the magnetic field lines are the stronger the magnetic force is
What part of the magnet has the strongest magnetic force? How can you tell?
AT THE POLES – magnetic field lines are closest together!

16. Magnetic Field Interactions
Two Like Poles
Two Opposite Poles

17. The earth as a magnet.
Scientists think that the earth’s magnetic field is made by the movement of electric charges in the Earth’s liquid outer core, which is made out of iron and nickel.
When the Earth rotates, the liquid in the core flows
When the liquid flows, electric charges move, which makes a magnetic field

18. Using a compass How does a compass work?
The compass needle points north because its north pole is attracted to the earth’s magnetic south pole.
What does this mean then?
The earth has a very strong magnetic field

20. Northern/southern lights
Auroras are made by charged particles from the sun hitting oxygen and nitrogen atoms in the air.
The atoms become excited and give off light
Auroras at north pole are called northern lights, or aurora borealis
Auroras at south pole are called southern lights, or aurora australis

21. Why are auroras only at the poles?