Earth’s Magnetic FieldChapter 14

Lesson 3

What is a Magnet?

A magnet is any material that attracts iron and materials that contain iron.

Magnetic Poles

Any magnet has two ends, a north and a south pole. ◦Magnetic poles that are alike repel each other.◦Magnetic poles that are unalike attract each

other. Remember: “Opposites Attract!”

Where is the magnetic force is the strongest?◦At the poles

Magnetic Field

The area of magnetic force around the magnet is known as its magnetic field.

The field lines form loops from pole to pole, and never cross.

Magnetic Activity

Use the provided magnets and ziplock bag of iron filings to view the magnetic field.◦Where are most of the iron filings at? ◦What does this tell you about the strength of

the magnet?Test the theory of attraction and repulsion

of the North and South poles.

Earth’s Magnetic Field

Just like a bar magnet, Earth has a magnetic field around it and two magnetic poles.

Compasses are devices that have a magnetic needle that spins freely.

Earth’s Magnetic Field

Earth has a magnetic field because of the outer core (liquid iron) and inner core (solid iron) moving at different speeds.

Earth’s Magnetic Field

The magnetic poles are not in the same place as the geographic poles. The difference (angle) between the geographic north pole and the magnetic pole is known as magnetic declination.

Earth’s Protection

Earth’s Magnetic Field

Electricity and Magnetism