1. Properties of Magnets

2. Learning Targets
8.1 I can recognize and explain what causes magnetic fields. 8.2 I can identify the shape and direction of the magnetic field around a bar magnet.

3. Poles of Magnets
If you suspend a bar magnet from its center by a piece of string, it will act as a compass.
The end that points northward is called the north-seeking pole.
The end that points southward is called the south-seeking pole.
More simply, these are called the north and south poles.
All magnets have both a north and a south pole. For a simple bar magnet the poles are located at the two ends.

4. Properties of Magnets
Magnetic poles behave similarly to electric charges in some ways (they can attract and repel).
Unlike electric charges, a magnetic pole cannot be isolated—if you cut a magnet in half, the newly cut faces become new north and south poles.

5. How does a magnet affect the space around it?

6. “Fields” of Force
Both magnetic poles and electric charges have an ability to apply an invisible force on objects around them.
The space around an electric charge, in which an electric force can be exerted, is called an electric field.
The space around a magnet, in which a magnetic force is exerted, is filled with a magnetic field.
If we place another magnet or a small compass anywhere in the field, its poles will tend to line up with the magnetic field.

7. The North pole of a compass needle is repelled by the North pole of a magnet, so the compass needle points towards the South pole of the magnet.
So, we define the direction of a magnetic field to be pointing from North to South.

8. Whiteboard Challenge

9. Draw the magnetic field lines around the following magnet.

10. Draw the magnetic field lines around the following magnets.

11. Draw the magnetic field lines around the following magnets.

12. Draw the magnetic field lines around the following magnets.

13. Julius Sumner Miller Adventures in Magnetism: