1. Warm Up What is a current?
What is the difference between an open and closed circuit?
What are parallel and series circuits?
Warm Up

2. Brainpop: Magnetism

3. Magnetism is a Force That Acts at a Distance
Before, you learned
Now, you will learn
A force is a push or a pull
Some forces act at a distance
Atoms contain charged particles
How magnets attract and repel other magnets
What makes some materials magnetic
Why a magnetic field surrounds Earth

4. A Magnet… Always has a north pole and a south pole (dipole)
Like poles repel
Unlike poles attract

5. A Magnet… Always has a north pole and a south pole (dipole)
Like poles repel
Unlike poles attract
Has a magnetic field
Exerts a force on other magnets in the direction of the magnetic field
Is 3-dimensional
Exists inside and outside of the magnet
The magnetic field of a magnet is strongest at the poles

6. Magnetic Fields

7. Earth is a magnet
The magnetic field around Earth acts as if there were a large bar magnet that runs through Earth’s axis.
The source of Earth’s magnetic field is the movement in the core, which is mostly iron and nickel
The Northern Lights and Southern Lights occur near Earth’s magnetic poles, because these locations are where Earth’s magnetic field is strongest.

8. A Magnet… Always has a north pole and a south pole (dipole)
Like poles repel
Unlike poles attract
Has a magnetic field
Exerts a force on other magnets in the direction of the magnetic field
Is 3-dimensional
Exists inside and outside of the magnet
Induces magnetism in some materials (induced magnetism)
Magnetism – the force exerted by a magnt
Causes metals to act like magnets, thus causing pole attraction/repulsion
Can be demagnetized several ways including:
Placing into a large magnetic field
Banging on concrete

9. Types of
Magnets

10. Permanent Magnets
Placing magnetic materials in very strong magnetic fields makes permanent magnets

11. Bar Magnets (chrome-steel alloy)
Permanent
Magnets
Bar Magnets (chrome-steel alloy)
Horseshoe Magnets (nickel-cobalt-iron alloy)
Refrigerator magnets!

12. Temporary
Magnets
Iron Nails
Paper Clips

13. Magnetic Materials
In a material that is not magnetic, the magnetic fields of the atoms are weak and point in different directions.
In a material that is magnetic, the magnetic fields of a group of atoms align, or point in the same direction. A magnetic domain is a group of atoms whose magnetic fields are aligned.
A magnetic is a material in which the magnetic domains are all aligned.

14. Review What force causes magnets to attract or repel one another?
Why are some materials magnetic and not others?
Describe three similarities between Earth and a bar magnet?
A needle is picked up by a magnet. What can you say about the needle’s atoms?
The Northern lights can form into lines in the sky. What o you think causes this effect?