1. Unit 6: Magnetism Chapter 15: Magnetism
15.1 Properties of Magnets
15.2 The Source of Magnetism
15.3 Earth's Magnetic Field
10 Minutes

2. Explain how magnetic forces interact with each other.
OBJECTIVE 02/05/14
Explain how magnetic forces interact with each other.

3. Properties of magnets
If a material is magnetic, it has the ability to exert forces on magnets or other magnetic materials nearby.
A permanent magnet is a material that keeps its magnetic properties.

4. Properties of Magnets
All magnets have two opposite magnetic poles, called the north pole and south pole.
If a magnet is cut in half, each half will have its own north and south poles.

6. Magnetic force
Magnetic forces can pass through many materials with no apparent decrease in strength.

7. Magnetic fields
The force from a magnet gets weaker as it gets farther away.
Separating a pair of magnets by twice the distance reduces the force by 8 times or more.

8. Magnetic fields
You can actually see the pattern of the magnetic field lines by sprinkling magnetic iron filings on cardboard with a magnet underneath.

9. The magnetic field
All magnets create a magnetic field - one of the many lines with arrows used to show the directions of forces.
Away from North Pole
Toward South Pole
The number of field lines in a certain area indicates the relative strength of the magnetic field in that area. The
closer the lines are together, the stronger the field. The arrows on the field lines
indicate the direction of the force 9

10. Magnetic force
Magnetic forces are used in many applications because they are relatively easy to create and can be very strong.
Large magnets, such as this electromagnet, create forces strong enough to lift a car or a moving train.

11. 15.1 Investigation: Magnetism
Key Questions:
How do magnets and compasses work?
Objectives:
Discuss the properties of permanent magnets.
Measure magnetic force.
Use a compass to detect magnetic force.