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

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

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.

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.

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

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.

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

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

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.

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.