# Forces of Nature

#### Lab Assignment: Magnetic Fields

Forces of Nature Lab

# The Structure of Magnetic Fields

## Goal: To determine the field lines of a magnet and magnetic strength.

#### Materials

• At least three magnets
• A compass (you can get these at educational stores; the Boy Scouts have great affordable compasses.)
• Large sheets of paper
• Paper clips (lots of these)
• Pencil

#### Map Field Extent (2 magnets)

1. Place one of the magnets on a sheet of paper.
2. Put a compass anywhere on the paper.
3. Mark the north end of the compass with an arrow > in the direction the magnet points.
4. Mark the south end of the compass with a dot.
5. Move the compass and draw a line between the . and the >. This is a short representation of the magnetic field line at that point.
6. Map at least 20 different positions for your magnet.
7. Try to determine where the magnet's field dissipates and the earth's magnetic field takes over.
8. Measure the distance from the magnet to the edge of its field.
9. Repeat the procedure with one of the other magnets

#### Map Magnetic strength (all magnets)

1. Have each magnet pick up a paper clip.
2. Add paper clips in a chain (physically linked, not just drawn by the magnet), until you find the maximum number of clips the magnet can hold. This is its "clip strength".

#### Prediction

1. Based on "clip strength" of each unmapped magnet, predict the distance from the magnet to the edge of its field.
2. Measure the fields as you did above for the previously unmapped magnets.

#### Data Handling

1. Show how you calculated or estimated the field extent of the unmapped magnet from the clip strength.
2. Explain any differences between your estimated field size and your measured field size.

#### Report

1. Describe your materials, equipment, an dprocedures in sufficient detail that your fellow students could repeat your experiment.
2. Report your data. Be sure to indicate the amount of error in your measurements. For example, if you can only measure a mass of 25 gms within 1 grm, your error would be 25 ± 1, or 1/25 = 4%.
3. Present your data in an organized form, preferably in a table, in such a way it is easy to compare results as you repeate trials or vary a specific contributing factor.
4. Show a sample calculation, if you have calculated values.
5. If you did a series of experiments, varying something by increasing or decreasing a factor, try to plot your data (y-axis) as a function of the factor (x-axis).