Basic Magnetic Properties

1. Basic Magnetic Properties Magnets are fun to play with.

2. Magnetic materials • Certain materials are “magnetic” or can retain magnetic properties. These include iron, nickel, and cobalt. • Magnetic materials were originally found in the ground. • Today magnets are “made” by placing materials in a strong magnetic field

3. The Poles • Magnets have a North and South pole • The Poles exist together in pairs, can’t separate a North from a South

4. Magnetic field lines • Field lines leave the North and enter the south • A compass (which is a magnet) aligns itself with the North pointing in the direction of the magnetic field lines

5. Making Magnets • Magnets are made by placing magnetic materials in a strong magnetic field • In these materials the little magnetic dipoles all line up, creating a North at one end and a South at the other.

6. Why does magnetism exist? • Magnetism exists because moving charges create magnetic fields. • These moving charges create little baby magnets inside the material. When all these little baby magnets line up, they create one big magnet

7. Break a magnet in half? • Breaking a magnet in half just creates two smaller magnets

8. Earth’s magnetic field • The earth has a magnetic field. • A compass aligns itself with this field, with the North side of the compass point towards the magnetic South. • We call the North pole the North pole because the North on the compass points in this direction. • The “North Pole” is actually magnetically South • There is evidence that every few gazillion years the poles reverse. • The magnetic fields are important for our survival as they deflect charged particles flying at us from the sun.

9. Earth’s magnetic field