Magnetism Pg. 76

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.

Magnetism

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.

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.

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

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”

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?

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

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

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

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

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

Poles of a magnet always Come in pairs!

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

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

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

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)

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

Magnetic Force https://www.youtube.com/watch?v=VHhk8Atatp0 https://www.youtube.com/watch?v=tC13_BkDieU https://www.youtube.com/watch?v=0t8yDnyOaQ8

Earth’s Magnetic Force https://www.youtube.com/watch?v=yEYy_nVC4L0

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…

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