Bursts of Energy...
Building an Electromagnet and Measuring Its Strength

Electricity and Magnetism

Goal:  Students will explore electricity by building an electromagnet.

Process skills:

• Applying concepts
• Classifying
• Collecting data
• Communicating
• Estimating
• Hypothesizing
• Controlling variables
• Making graphs
• Measuring
• Observing
• Predicting

Frameworks: Force and Motion

Materials: (per student group)

• nails or bolts (5-6 inches long)
• iron filings
• one sheet heavy cardstock
• two feet of insulated wire — narrow gauge winding wire
• one 6 volt battery with battery connector clips
• wire stripper
• one 5-6 in. long permanent bar magnet
• steel washers
• paper clips
Teacher background information:
In 1831, a scientist named Michael Faraday found that a magnet could be used to produce electricity. Faraday moved a strong magnet back and forth through a coil of wire. The magnetic field produced by the magnet caused the electrons inside the wire to move resulting in an electric current. Faraday's discovery is the basis for a machine that is still in use today — the generator. A generator changes the energy of motion into electrical energy. When coils of wire cut through a magnetic field, electrons move through the wire. To keep the electrons moving, the wire or the magnet must be kept moving. In an electromagnet, the process is reversed: electrical current produces a magnetic field. In this case, the magnetic field only exists while the electric current is flowing.

Procedure:
Student groups will:

1. Discuss and investigate permanent magnets and electromagnets with students. Introduce the concept of permanent magnets and electromagnets.

Students will:
2. Investigate permanent magnets and test them for strength. Test how many paper clips the magnet will pick up at a time. Record data.
3. Make a washer into a magnet by rubbing it on the permanent magnet in one direction. Test its strength by counting how many paper clips will it pick up. Record this data.
4. Investigate magnetic fields. Sprinkle iron filings on a piece of heavy card stock and place a permanent magnet under the card stock. Observe and record what happens. Test the washer magnet in the same way and observe and record observations.
5. Pass out materials for groups (nail, winding wire, shared wire stripper).
6. Using the materials, build an electromagnet:
• Wind the wire (about 2 feet) carefully and tightly around the nail. Leave three inches free on each end and remove the insulation from the free ends.
• Attach one of the free wire ends to one end of the battery holder and the other end of the wire to the other end of the battery holder (See Photo).  Students can do this activity without a battery holder by using clips to hold the wires to the battery. Predict how strong the electromagnet will be (How many paper clips will it hold?). Test predictions and record the number of paper clips it holds.
7. Using their results, hypothesize bow they can increase or decrease the strength of an electromagnet.
8. Experiment and record their findings.
9. Compare their results with other groups.

Discussion:

1. Was the electromagnet as strong as the permanent magnet? Why or why not?
2. How was the nail able to pick up the paper clips?
3. Were you able to make the electromagnet stronger? How?

Extension:

1. Have students make another electromagnet with twice as much wire.
2. How does the strength of the second electromagnet compare with the first?

Teacher resources:
Ardley, Neil. The Science Book of Magnets Gr. 2-6.
This book contains simple experiments to illustrate the principles of magnetism. Other energy-related titles in this series including Water, Light, Sound, Motion, Energy, Machines, Electricity, and Weather. ISBN: 0-1)-365405-8

Gardner, Robert. Electricity and Magnetism Gr. 6 & Up. This book features 17 activities dealing with static electricity, magnetism, electro-magnetism. and basic electrical properties such as simple circuits. Gardner fits his demonstrations into a historical narrative that is sprinkled with contemporary "gee-whiz" tidbits-for example, the role of static electricity in photocopiers, and magnetism as a possible cause of whales beaching themselves. ISBN: 0-80-502850-1

Pfeffer. Wendy. Marra's Magnets Gr. 2-4. Marta's sister, Rosa, calls her magnet collection "junk" hut Marta's magnets help her make friends in her new home and help her retrieve a lost key for Rosa's new friend. This is an excellent multicultural science-literature connection. ISBN: 0-382-24930-5

Robson, Pam. Science Workshop: Magnetism Gr. 2-6. Robson explores the properties of magnets and ways to work with the forces of attraction and repulsion. Easy-to-make science experiments with clear explanations as to how and why they work are included. ISBN: 0-15-365405-8

Vecchione, Glen. Magnet Science Gr. 5-9. From the discovery of the lodestone (an ancient Greek legend) to the use of magnetic technology in the space program, this book introduces the science of magnets. Activities vary from simple (magnetizing a screwdriver) to practical (building a motor) to playful (making a magnetic hockey game) to out-of-this-world (collecting and identifying micrometeorites). ISBN: 0-8069-0888-2