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# More Muscle: What Part of a Magnet Has The Strongest Attracting Ability?

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Source:
Author: Janice VanCleave

### Problem

What part of a magnet has the strongest attracting ability?

### Materials

• scissors
• ruler
• string
• bar magnet
• masking tape
• box of about 100 small paper clips large bowl

### Procedure

1. Cut two 3-foot (1-m) pieces of string.
2. Tie one end of each string to each end of the magnet.
3. Tape the free ends of the strings to the top of a door frame.
4. Adjust the length of the strings so that the magnet hangs in a level position and is at a height that is easy for you to reach.
5. Spread the paper clips in the bottom of the bowl.
6. Raise the bowl so that the magnet touches the paper clips.
7. Slowly lower the bowl.
8. Observe where the clips cling to the magnet

### Results

Most of the clinging paper clips are near the ends of the magnet.

### Why?

All magnets are surrounded by an area called a magnetic field. This area is made of invisible lines of force coming out of the north pole of the magnet, around each side, and into the south pole of the magnet. The magnetic force lines are closest together at the poles, which makes the poles have the strongest magnetic attraction.

### Let's Explore

1. Would the shape of magnetic materials affect how they are attracted to the magnet? Repeat the experiment, replacing the paper clips with other materials such as BBs and nails. Science Fair Hint: Display photographs taken of the experiment to demonstrate the strongest magnetic part of each magnet.
2. Does the shape of the magnet affect its areas of strength? Repeat the original experiment using several different magnets, including round and horseshoe-shaped magnets. Raise the bowl and allow the entire magnet to touch the paper clips. Science Fair Hint: Secure a support beam across the top of your project display frame. Hang the magnets you used in the experiments so that you can show the magnetic material clinging to them.

### Show Time!

Test the "muscle strength," or supporting power, of the poles of different-shaped magnets by taping them to a table so that part of each magnet extends over the edge. Bend open the end of a paper clip so that it forms a hook and touch it to the bottom of an extended magnet. (Do not hook it over the magnet.) Do this for each magnet. Add paper clips one at a time to each open clip until the clip pulls loose from the magnet and falls.

### Check It Out!

Just as the poles of any magnetic object have a stronger magnetic pull than the rest of the object, the earth's magnetic poles have a stronger magnetic pull than the rest of the planet. Electrical particles that stream out from the sun are pulled toward the earth's magnetic poles. These electrical particles produce glowing lights in the sky called aurora borealis at the earth's North Pole and aurora australis at the earth's South Pole. Write a report on exactly how these colored lights in the sky are produced. (Information can be found on pages 104-105 of Astronomy for Every Kid [New York: Wiley, 1991], by Janice VanCleave.)

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