Bolded words are vocabulary and concepts to highlight with students during the activity.
What is an electromagnet? The two types of magnets are permanent magnets and electromagnets. Students are probably familiar with permanent magnets—they are the ones that stick to refrigerator doors. They are called permanent magnets because they always have magnetic fields. Electromagnets are different because their magnetic fields are created by current running through them, meaning the magnetic fields can be removed by turning off the electricity. Today, students make electromagnets and experiment with ways to change their strength.
- 1 D-cell battery (fully charged)
- 1 3-inch (7.6-cm) iron nail
- 1 wide rubber band
- 2 x 2-inch (5 x 5-cm) piece of 150 grit sandpaper
- 4 paperclips
- 24 inches (61 cm) magnet wire (at least AWG 22 or higher)
- blank paper
Working in groups of three, students make magnets that each consist of magnet wire, a battery and an iron nail. Students wrap wire around the nail, manipulating the current and creating a magnetic field. Then they use their electromagnets to pick up paperclips, counting how many they can pick up. Also, they experiment with different methods of wrapping the wire in order to create the strongest magnets possible.
Building and Testing
- Divide the class into groups of three students each. Hand out the supplies.
- Have groups sand the coating off the last quarter-inch of each end of the wire (this is where the wire connects to the battery).
- Have students wrap the magnet wire around the nail—in whichever manner they choose, leaving approximately 2 inches of wire free on each end of the nail (see image above). Advise students to wrap their nails at least 20 times and wrap the copper coils tightly, leaving no gaps between wraps. Later, they have an opportunity to experiment with different ways of wrapping the wire, so encourage them to be creative and think outside the box.
- Have groups draw and describe their current wire configuration on paper. Remind them to be specific: how many times did they wrap the wire around the nail? Did they wrap it tightly or loosely around the nail?
- Direct students to hold a wire end on each end of the battery, and secure the wires by wrapping the battery with a rubber band (see image above).
- Students are now able to pick up paperclips with their magnets. Instruct them to count how many paperclips they can collect on the tip of the nail.
- Have students record on the back side of the paper how many paperclips they picked up with their current wire configuration. Call this Trial 1.
- Have students try many different configurations. Have them keep track of each of configuration, recording their findings as Trial 2, Trial 3, etc.
- At the end of the class, ask groups to share the maximum number of paperclips they were able to pick up, and how that electromagnet was configured to achieve the best results.
Wrap Up - Thought Questions
- Which electromagnet designs worked the best? Why?
- Why might engineers want to use an electromagnet rather than a permanent magnet?
- Keeping the same wire configuration, how else could you increase the strength of your electromagnet?
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Last modified: May 11, 2016