Download Electromagnet - Cascades Science Center Foundation

Electromagnet
Your Activity
Build a simple electromagnet
Material
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Long nail (3 inches)
Insulated wire
Wire stripper
6-V battery
Paper clips and other metal objects
Electric Tape
(Optional) Knife Switch
Create
1. Cut a piece of insulated wire about two feet long
2. String one inch of insulation off each end of the wire
3. Wrap the wire tightly around the nail (at least 40 times), leaving a few inches of wire hanging off at each end
of the nail.
4. Connect each end of the wire to the battery terminal
5. Test the nail to see that now it is magnetic. Use it to pick up some paper clips or other small objects.
6. (Bonus) Add a switch to turn electromagnet on and off
7. (Bonus) What happens if you add two batteries to the circuit?
Science Topics
Electromagnetism, Electricity, Electric Circuit
What’s going on?
Electromagnets are used in all sorts of machines, from door bells, MRI machines to giant scrap yard cranes. Electricity and
magnetism are closely related phenomena. A current passing through a coil will give rise to a magnetic field. When the electric
current passes through the wire round around the nail, it creates a magnetic field that reaches out in expanding circles. The
magnetic field magnetizes the metal as if it were a permanent magnet. While the regular magnets need to stay “on” all the times,
the electromagnet may be turned off. The strength of the magnet is directly related to the number of times the wire coils around
the rod. For a stronger magnetic field, the wire should be more tightly wrapped.
Caution: The 6 volt battery is capable of sending lot of current into this electromagnet. Never touch the exposed electric contacts. The device may heat
up if left on for too long. Continuous use will quickly drain the battery. Children should only use this device with adult supervision.
Electromagnet
Activity Lead Notes
Introduction
People use the power of magnets in many ways. Magnetism and electricity are closely related. In an electric generator,
an electric current is set up in a coil of wire that moves through a magnetic field. An electric current moving through a
wire coil wrapped around an iron core produces magnetism. The close interrelationship between magnetism and
electricity has many applications. In this lesson, students will make a simple electromagnet by wrapping a wire around a
nail and attaching the ends of the wire to a battery to make an electric circuit. As current flows through the coil, a
magnetic field is produced and the nail is magnetized. Lessons such as this help to build a foundation upon which
students can develop their ideas about gravitational force and how electric currents and magnets can exert a force as
well.
Learning Objectives
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To learn how to construct and use an electromagnet.
To learn that electromagnets are temporary magnets and work only when electricity passes through the coil of
wire.
Background
Begin with a brief discussion in which students can review concepts about magnetism, using questions such as these:
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What is a magnet?
What is a magnetic field?
Can you make a magnet?
Then say to students, “Electromagnets are temporary magnets that let us turn magnetic fields on and off so we can
control the magnetic energy.” Then ask students to speculate on why it is advantageous to turn the fields on and off. Tell
students that they will conduct an activity to explore how electromagnetic fields work.
Talk about how electromagnets are used in speakers, electric bells and electric motor.
Materials
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See activity sheet for material to make slime
Snap Circuits Electromagnetism Kit
Preparing Materials
To save time, you can pre-strip the ends of the wire for each pair of students. You can use a wire stripper, scissors, or a
sharp knife to remove the insulation.
Procedure
Start with doing a demo of the Snap Circuits electromagnet kit.
Before students begin to work on their own, make sure that each group has the needed materials to build their
electromagnet. To help students, you can ask questions such as the following before they begin:
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Do you think an electromagnet will be attracted to the same things as a regular magnet?
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Will it be attracted to all metal things?
Will it be attracted to other magnets?
As students are building the electromagnet, walk around the class to make sure that they are on track. Ask questions
such as:
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What happens to the electromagnet if you disconnect one of the wires from the battery?
How many turns of the wire does it take to pick up a paper clip?
Are more turns better?
After students have built their electromagnet and tested it, you could ask questions such as the following to extend
their ideas:
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What happens if you build another electromagnet using a different size battery?
How many paper clips will this new electromagnet pick up?
Does using a different size battery (“A” versus “C”) make a difference?
What things are attracted to a permanent magnet, such as a refrigerator magnet? Are these the same things
that are attracted to the electromagnet?
Are there any differences between what the permanent magnet and the electromagnet can do?
After students have completed te activity, discuss these questions:
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What is traveling through the wires? Where does the electricity come from?
Is an electromagnet a temporary magnet or a permanent magnet? Why is it a temporary magnet?
How can you measure the strength of your electromagnet? How can you make your electromagnet stronger?
Takedown
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Do not dismantle the electromagnets until you are finished with electromagnet activities, but be sure they are
disconnected from the batteries at the end of your class.
When you are finished with electromagnet activities, unwrap the wires and be sure the electromagnets are not
connected to the batteries.
Return all equipment and supplies to the storage.
Safety & Disposal
The wire is hot when connected to the battery.
Source
http://sciencenetlinks.com/lessons/build-an-electromagnet/