Chapter 7Electromagnetism

(Magnets and Magnetism)

What is a Magnet?

Any material that can attract iron or any material that contains iron.

Properties of Magnets

Magnetic effects are strongest at the ends (poles) of the magnet Two different poles

North and South

Magnetic Forces Very similar to electric charges

opposite poles attract, like poles repel

The north pole of the guideway’s magnet should face it.

The train uses less energy because there is very little friction. The train and the track get less wear. The train has a smoother ride.

Magnetic Fields

The magnetic field is the region around the magnet in which magnetic fields can interact.

Why Materials are Magnetic

Electrons move inside the atom which produce magnetic fields creating north and south poles within the atom

In magnetic materials, the atoms group together in regions called domains

Domains

Domains are like little magnets with a north and south pole

All of the atom’s magnetic fields line up with the fields of the domain

Magnetic DomainsIf the domains are

aligned, the material is magnetic

Atoms that are

aligned create a strong magnetic field

If the domains are not aligned, then the material is not

magnetic

Figure 2 – pg 202

Figure 2- pg 203

You can feel the magnets repel or

attract each other.

The magnetic field is too weak at that distance.

Earth is a Magnet

Earth’s magnetic South poleis lined up with Earth’s geographical North pole.

How is the Earth magnetic?

Earth’s magnetic field is produced by movement of electric charges

The core of the Earth is made of iron and nickel. It is a solid because of major pressure

The outer core is a liquid As the earth rotates, the liquid causes the electric

charges to move, generating a magnetic field

Do the Math – pg 205

The pole has moved 857 km(150+120+120+180+287=857 km

857 km / 53 years = 16.2 km/yr

Bar magnet

Cylindrical magnets Horseshoe magnets

Cow magnets

Disk/Ceramic magnets