GO IN DEPTH

# Exploring Magnetic Fields: Activity 2

### Introduction

Around every magnet, there is an invisible field called a magnetic field. This field is what attracts items such as paper clips and nails to the magnet. Although it is invisible, we know that we can see the effects of this invisible field in the pattern that is made by iron fillings when we expose them to a magnet. Now let’s explore these fields some more.

As you are working, answer the questions below and fill out the data table when necessary.

What You Need

• 2 bar magnets
• Paper clip
• Pen or pencil for drawing pictures
• Ziploc® bags with a 3 x 5-inch index card and iron filings inside

1. Lay the plastic bag on a table and shake it gently back and forth until you get a thin layer of filings on top of the index card in your bag. The filings should not all be in a lump at one end.

2. Lay your paper clip on the other end of your desk. When you have a nice layer of filings on the index card in your bag, gently lift up the bag and hold it right over the paper clip. What happens? Do the filings move around? Describe it below.

3. Now, lay your magnet on the other end of your desk. Again, shake your bag so that you have a thin layer of filings on the index card. Then gently lift up your bag and hold it right over the magnet. What happens? Do the filings move around? Try it a few times. You can hold the magnet flat in your hand and set the bag down on it there, too. Draw a picture of the magnetic field you see in your bag on your data sheet.

Remember: We cannot really see the magnetic field, but we can see how it moves the iron filings around. This is like the wind outside. We cannot see the wind, but we can see how it moves the leaves on the trees or paper in the street.

4. Now put your other bar magnet under the zipper-lock bag. Does the magnetic field of this magnet look like the first one? Try some other bar magnets and compare with those of other teams of students.

5. Now, put your two bar magnets end-to-end so that they are attracted to each other and then put your zipper-lock bag on top. What do the magnetic fields of the two magnets look like now? Draw a picture on your data sheet.

6. Next, put your two magnets end-to-end so that they repel each other. Set your zipper-lock bag on top and see if the fields look different. Draw a picture on your data sheet of what you see. Look at your pictures. Can one magnetic field change the shape of another magnetic field when they get close to each other? What do your drawings show you about this?

7. Now ask your teacher for another magnet of a different shape. This magnet might be shaped like a doughnut or a horseshoe. Try to see what the magnetic field looks like around this magnet. Draw a picture of it on your data sheet. Do all magnetic fields look alike? Do they change shape with the shape of the magnet?

8. Why do you think the iron filings line up along the magnetic field as they do?

Exploring Magnetic Fields Data Sheet

 What does the magnetic field look like around your bar magnet? Draw a picture of what you see. What does it look like when you have two magnets under the zipper-lock bag that are attracted to each other? Draw a picture of what you see. What does it look like when the two magnets are repelling each other? Draw a picture of what you see. What does the magnetic field look like around a horseshoe or doughnut magnet? Draw a picture of what you see.