• Visit
    • Calendar
    • After Dark Thursdays
    • Buy Tickets
    • Exhibits
    • Museum Galleries
    • Artworks on View
    • Hours
    • Getting Here
    • Visitor FAQ
    • Event Rentals
    • Field Trips
  • Education
    • Professional Development Programs
    • Free Educator Workshops
    • Tools for Teaching and Learning
    • Learning About Learning
    • Community Programs
    • Educator Newsletter
  • Explore
    • Browse by Subject
    • Activities
    • Video
    • Exhibits
    • Apps
    • Blogs
    • Websites
  • About Us
    • Our Story
    • Partnerships
    • Global Collaborations
    • Explore Our Reach
    • Arts at the Exploratorium
    • Contact Us
  • Join + Support
    • Donate Today!
    • Membership
    • Join Our Donor Community
    • Engage Your Business
    • Attend a Fundraiser
    • Explore Our Reach
    • Thank You to Our Supporters
    • Donor & Corporate Member FAQ
    • Host Your Event
    • Volunteer
  • Store
  • Visit
    • Frequently Asked Questions
    • Calendar
      • Today
      • This Week
      • Online
      • After Dark Thursday Nights
      • Arts
      • Conferences
      • Cinema Arts
      • Free + Community Events
      • Fundraising Events
      • Kids + Families
      • Members
      • Special Hours
      • Private Event Closures
    • Prices
    • Hours
    • Getting Here
    • Museum Map
    • Free Admission and Reduced Admission
    • Accessibility
    • Tips for Visiting with Kids
    • How to Exploratorium
    • Exhibits
    • Tactile Dome
    • Artworks on View
    • Cinema Arts
    • Kanbar Forum
    • Black Box
    • Museum Galleries
      • Bernard and Barbro Osher Gallery 1: Human Phenomena
        • Tactile Dome
          • 1971 Press Release
        • Black Box
        • Curator Statement
      • Gallery 2: Tinkering
        • Curator Statement
      • Bechtel Gallery 3: Seeing & Reflections
        • Curator Statement
      • Gordon and Betty Moore Gallery 4: Living Systems
        • Curator Statement
      • Gallery 5: Outdoor Exhibits
        • Curator Statement
      • Fisher Bay Observatory Gallery 6: Observing Landscapes
        • Wired Pier Environmental Field Station
        • Curator Statement
    • Restaurant & Café
    • School Field Trips
      • Getting Here
        • Bus Routes for Field Trips and Other Groups
      • Admission and Tickets
      • Planning Guide
      • Reservations
        • Field Trip Request Form
      • Resources
    • Event Rentals
      • Full Facility & Gallery Bundles
      • Fisher Bay Observatory Gallery & Terrace
      • Moore East Gallery
      • Bechtel Central Gallery & Outdoor Gallery
      • Osher West Gallery
      • Kanbar Forum

      • Weddings
      • Proms and School Events
      • Daytime Meetings, Events, & Filmings
      • Happy Hour on the Water

      • Rentals FAQ
      • Event Planning Resources
      • Rental Request Form
      • Download Brochure (pdf)
    • Groups / Tour Operators
      • Group Visit Request Form
    • Exploratorium Store
    • Contact Us
  • Education
    • Black Teachers and Students Matter
    • Professional Development Programs
      • Free Educator Workshops
      • Professional Learning Partnerships
      • Teacher Institute
        • About the Teacher Institute
        • Summer Institute for Teachers
        • Teacher Induction Program
        • Leadership Program
        • Teacher Institute Research
        • CA NGSS STEM Conferences
          • NGSS STEM Conference 2020
        • Science Snacks
          • Browse by Subject
          • Special Collections
          • Science Snacks A-Z
          • NGSS Planning Tools
          • Frequently Asked Questions
        • Digital Teaching Boxes
        • Meet the Teacher Institute Staff
        • Resources for Supporting Science Teachers
      • Institute for Inquiry
        • What Is Inquiry?
        • Watch and Do Science
        • Inquiry-based Science and English Language Development
          • Educators Guide
            • Conceptual Overview
              • Science Talk
              • Science Writing
            • Classroom Video Gallery
              • Magnet Investigation
              • Snail Investigation
            • Teacher Professional Development
            • Project Studies
            • Acknowledgments
          • Conference: Exploring Science and English Language Development
            • Interviews with Participants
            • Plenary Sessions
            • Synthesis, Documentation, and Resources
        • Workshops
          • Participant Portal
          • Fundamentals of Inquiry
            • Summary Schedule
          • BaySci Science Champions Academy
          • Facilitators Guides
          • Commissioned Workshops
        • Resource Library
        • Meet the IFI Staff
      • Resources for California Educators
      • K-12 Science Leader Network
      • Resources for Supporting Science Teachers
      • Field Trip Explainer Program
      • Cambio
    • Tools for Teaching and Learning
      • Learning Toolbox
      • Science Snacks
      • Digital Teaching Boxes
      • Science Activities
      • Tinkering Projects
      • Recursos gratuitos para aprender ciencias
      • Videos
      • Exhibits
      • Publications
      • Apps
      • Educator Newsletter
      • Exploratorium Websites
    • Educator Newsletter
    • Advancing Ideas about Learning
      • Visitor Research and Evaluation
        • What we do
        • Reports & Publications
        • Projects
        • Who we are
      • Center for Informal Learning in Schools
    • Community Programs
      • High School Explainer Program
      • Xtech
      • Community Educational Engagement
      • California Tinkering Afterschool Network
        • About
        • Partners
        • Resources
        • News & Updates
        • Further Reading
  • Explore
    • Browse by Subject
      • Arts
      • Astronomy & Space Sciences
        • Planetary Science
        • Space Exploration
      • Biology
        • Anatomy & Physiology
        • Ecology
        • Evolution
        • Genetics
        • Molecular & Cellular Biology
        • Neuroscience
      • Chemistry
        • Combining Matter
        • Food & Cooking
        • Materials & Matter
        • States of Matter
      • Data
        • Data Collection & Analysis
        • Modeling & Simulations
        • Visualization
      • Earth Science
        • Atmosphere
        • Geology
        • Oceans & Water
      • Engineering & Technology
        • Design & Tinkering
        • Real-World Problems & Solutions
      • Environmental Science
        • Global Systems & Cycles
        • Human Impacts
      • History
      • Mathematics
      • Nature of Science
        • Measurement
        • Science as a Process
        • Size & Scale
        • Time
      • Perception
        • Light, Color & Seeing
        • Listening & Hearing
        • Optical Illusions
        • Scent, Smell & Taste
        • Tactile & Touch
      • Physics
        • Electricity & Magnetism
        • Energy
        • Heat & Temperature
        • Light
        • Mechanics
        • Quantum
        • Sound
        • Waves
      • Social Science
        • Culture
        • Language
        • Psychology
        • Sociology
    • Browse by Content Type
      • Activities
      • Blogs
        • Spectrum
          • Arts
          • Behind the Scenes
          • News
          • Education
          • Community & Collaborations
          • Science
        • Eclipse
        • Studio for Public Spaces
        • Tangents
        • Resonance See & Hear Blog
        • Fabricated Realities
        • Tinkering Studio: Sketchpad
        • Exploratorium on Tumblr
      • Exhibits
      • Video
      • Websites
      • Apps
        • Total Solar Eclipse
  • About Us
    • Our Story
    • Land Acknowledgment
    • Explore Our Reach
    • Impact Report
    • Awards
    • Our History
      • 50 Years 1969–2019

    • Leadership Cabinet
    • Board of Trustees
    • Board of Trustees Alumni
    • Staff Scientists
    • Staff Artists

    • Arts at the Exploratorium
      • Artworks on View
      • Artist-in-Residence Program
      • Cinema Arts
        • History and Collection
        • Cinema Artists-in-Residence
        • Resources and Collaborating Organizations
        • Kanbar Forum
      • Center for Art & Inquiry
        • Begin Here
          • Lessons
            • Bob Miller/Light Walk
            • Ruth Asawa/Milk Carton Sculpture
          • Workshops
      • Resonance
        • About the Series
        • See & Hear
        • Past Seasons
      • Over the Water
      • Black Box
      • Upcoming Events
      • Temporary Exhibitions
      • Arts Program Staff
    • Teacher Institute
    • Institute for Inquiry
    • Explainer Programs
    • Studio for Public Spaces
    • Exhibit Making
    • Partnerships
      • Building Global Connections
        • Global Collaborations
          • Projects
          • Approach
          • People
          • Impact
      • Partnering with Science Agencies
        • NASA
        • NOAA
      • Partnering with Educational Institutions
      • Osher Fellows

    • Job Opportunities
    • Become a Volunteer

    • Contact Info
    • Newsletter
    • Educator Newsletter
    • Blogs
    • Follow & Share
    • Press Office

    • FY21 Audit Report
    • 990 FY20 Tax Return
    • Use Policy
      • Privacy Policy
      • Intellectual Property Policy
  • Join + Support
    • Donate Today!
    • Membership
      • Membership FAQ
      • Member Benefits
      • After Dark Membership
      • Member Events
      • May Is for Members
    • Join Our Donor Community
    • Engage Your Business
      • Corporate Membership
      • Luminary Partnerships
    • Attend a Fundraiser
      • Wonder Funday
      • Science of Cocktails
      • Party at the Piers
        • Event Leadership and Host Committee
    • Explore Our Reach
    • Thank You to Our Supporters
    • Donor & Corporate Member FAQ
    • Volunteer
      • How to Apply
      • Application for Internships
      • Our Contract
      • Application for Individuals
  • Press Office
    • Press Releases
    • News Coverage
    • Events Calendar
    • Photographs
    • Press Video
    • Press Kits
    • Press Visits
    • Exploratorium Logos
    • Recent Awards
    • Praise for the Exploratorium
    • Join Our Press List
  • Store

Masks and vaccinations are recommended. Plan your visit  

Visitor FAQ Buy Tickets Donate Today
Exploratorium
Exploratorium
  • Visit
    • Calendar
    • After Dark Thursdays
    • Buy Tickets
    • Exhibits
    • Museum Galleries
    • Artworks on View
    • Hours
    • Getting Here
    • Visitor FAQ
    • Event Rentals
    • Field Trips
  • Education
    • Professional Development Programs
    • Free Educator Workshops
    • Tools for Teaching and Learning
    • Learning About Learning
    • Community Programs
    • Educator Newsletter
  • Explore
    • Browse by Subject
    • Activities
    • Video
    • Exhibits
    • Apps
    • Blogs
    • Websites
  • About Us
    • Our Story
    • Partnerships
    • Global Collaborations
    • Explore Our Reach
    • Arts at the Exploratorium
    • Contact Us
  • Join + Support
    • Donate Today!
    • Membership
    • Join Our Donor Community
    • Engage Your Business
    • Attend a Fundraiser
    • Explore Our Reach
    • Thank You to Our Supporters
    • Donor & Corporate Member FAQ
    • Host Your Event
    • Volunteer
  • Store
Science Snacks
Science activity that demonstrates a magnetic field created by electromagnet
Science activity that demonstrates a magnetic field created by electromagnet
  • Science activity that demonstrates a magnetic field created by electromagnet
  • Science activity that demonstrates a magnetic field created by electromagnet

Circles of Magnetism

Make a magnetic field that's stronger than Earth's.

A compass allows us to observe the direction of a magnetic field: compass needles are just little magnets that are free to rotate. Normally, compasses respond to Earth’s magnetic field, orienting themselves parallel to magnetic field lines. If we create a magnetic field that is stronger than Earth's field—for example, by using electric currents—a compass needle will orient itself parallel to the new field.

Caution! Working with electricity can really heat things up! Always be careful with hot wires. And be sure that you don't leave the clip leads connected too long‚ because the electric current will rapidly drain the battery and may cause it to overheat. A few seconds should be long enough to make good observations.


Grade Bands: 
6-8
9-12
Subject: 
Physics
Electricity & Magnetism
Keywords: 
electromagnet
magnetic field
compass
exhibit-based
NGSS and EP&Cs: 
PS
PS2
CCCs
Patterns
Cause and Effect
Structure and Function

  • Facebook logo
  • Reddit logo
  • Twitter logo


Tools and Materials

  • PVC pipe and fittings for building the stand shown in the photos above (or one like it using materials and a design of your own choosing)
    • For the stand shown here, you'll need about 2 feet of 1/2-inch Schedule 40 PVC pipe, cut into the following lengths:
      • One 6-inch piece
      • One 4-inch piece
      • Two 3-inch pieces
      • Three 2-inch pieces
    • You'll also need the following fittings:
      • Two 90-degree elbows
      • Three T-joints
  • 12 feet (3.6 meters) of insulated copper wire that is stiff enough to retain the form of the square coil shown in the photo—12-gauge wire was used for this coil
  • Six small 4-inch cable ties (regular 8-inch cable ties can be used if small ties are unavailable)
  • One regular 8-inch cable tie
  • A hot-glue gun and hot glue sticks
  • A flat, rigid platform (ordinary cardboard works well) measuring approximately 8 × 8 inches (20 cm × 20 cm), into which you will cut a slit that is large enough to allow the coil of wire to pass through the center
  • Four to six small magnetic compasses, each measuring about 1 inch (2.5 cm) in diameter
  • Two electrical lead wires with alligator clips at both ends
  • One fresh D-cell battery
  • A battery holder of some sort to which you can attach the alligator clip leads (we put four nails in a small wooden block to hold the battery; one on each side to hold the battery and one at either end touching the terminals)
  • A PVC cutter
  • Utility knife (not shown)
  • Wire stripper (you can use the utility knife to strip the wire if a wire stripper isn't readily available)

Assembly

Constructing the stand:

Make one of your own design or follow the steps below to build a stand out of PVC. Note that it's not necessary to use PVC cement; friction fit will be ample to hold the stand together.

  1. Fit the PVC pieces together as shown in the photos above. Starting from the bottom, insert the 3-inch pieces into the two elbows and connect these to two of the 2-inch pieces and the straight part of a T-joint to form a U-shaped base. Swivel the T-joint so the top part is pointing up and insert the 4-inch piece. Add a T-joint and the 6-inch piece to complete the vertical part of the stand. Insert the remaining 2-inch piece and T-joint to make the part of the stand that will support your cardboard platform.
  2. Cut a 1/8- to 1/4-inch-wide slit from the center of one edge to the center of the cardboard piece.
  3. Glue the opposite edge of the cardboard to the part of the PVC stand (the T-joint attached to the 2-inch piece) that sticks out horizontally.

Making a square coil:

  1. Strip about 1 inch of insulation from one end of the copper wire.
  2. Leave about 1 1/2 inches of the stripped end, then measure another 10 inches and bend the wire 90 degrees. Measure about 10 more inches and bend 90 degrees again. Continue the process until you have formed a square "coil" with 10-inch-long sides—you should have three complete 4-sided square loops plus one additional side. Let this last, or thirteenth, side extend an additional 1½ inches and then cut the wire (you should have about a foot of wire left over, which you can discard or save for another use). Strip the insulation from the last inch of wire. The completed coil is shown in the photos above.
  3. Use the small cable ties to hold the wire together in the square coil shape.

Putting the whole thing together:

  1. Turn the square coil on its side, and orient it so the side with the two stripped ends runs vertically through the platform (see photo). Use the large cable tie to attach the coil to your PVC stand.
  2. Arrange the compasses in a circle on the cardboard as shown.
  3. Attach one end of a clip lead to each of the stripped ends, but do not attach the other ends of the clip leads to the battery yet.

To Do and Notice

Observe the compass needles when there is no current passing through the wire. Rotate the cardboard platform. What happens to the compass needles? They will point north, orienting themselves so that they are parallel to Earth’s magnetic field. (Note: A few of your compasses may point south! Inexpensive compasses that are exposed to a strong magnet will sometimes become magnetized in the reverse direction. It’s nothing to worry about, though—just keep in mind which end of each compass points north.)

Now attach the clip leads to the battery terminals. Watch what happens to the compass needles as current passes through the coil. (CAUTION: Don't leave the battery connected for more than several seconds at a time—the electric current can rapidly drain the battery and may cause it to overheat.) If the electrical current is large enough, each compass will point in a direction tangent to a circle centered on the vertical coil wires that they surround.

Rotate the cardboard platform again. What happens to the compass needles this time? The compasses will continue to point in a direction tangent to a circle centered on the vertical coil wires.

Switch the clip leads to the other terminals of the battery. What happens? The compass needles will reverse direction when the electrical current reverses direction.


What’s Going On?

Compass needles line up with magnetic fields. Since Earth is a magnet, a compass will normally line up with Earth’s magnetic field. Because opposite magnetic poles attract, the magnetic north pole of the compass points toward the magnetic south pole of the Earth. (The magnetic south pole of the Earth is located in northern Canada—that is not a misprint. Indeed, the magnetic south pole of the Earth is near the geographic north pole. To make things even more confusing, mapmakers call this the north magnetic pole.)

Electric current passing through a wire creates a magnetic field. In the vertical side of the coil, there are four wires and the current is the same size and moving in the same direction in all of them. Thus the compasses are sensing the magnetic field produced by a current four times larger than if they were surrounded by just one of the wires. This allows the use of a D-cell battery rather than a larger and more expensive battery that would be necessary to produce an equivalent current in a single wire.

The electric current passing through the vertical side of the coil creates a magnetic field that is stronger than Earth’s field (in a region close to the wires). You can visualize the shape of this new field as a set of concentric circles surrounding the vertical coil wires. The closer to the vertical coil wires you are, the stronger the magnetic field. The compass needles align themselves with the total magnetic field at each point, the sum of Earth’s field and that of the wire. Since the magnetic field from the vertical coil wires is significantly larger than that from Earth, each needle ends up pointing essentially in the direction of the magnetic field of the wire.

When you reverse the current, the direction of the magnetic field also reverses, and the needles dutifully follow it.


Going Further

To find the direction of the magnetic field made by an electrical current, you can use a technique called the right-hand rule.

Place your right hand with the thumb parallel to the wire carrying the current. Point your thumb in the direction of the electrical current in the wire. (Remember: The electric current flows from the plus side of the battery through the wire to the minus side.) Wrap your fingers around the wire. Your fingers will now point in the direction of the magnetic field around the wire. If there are compasses near the wire, they will point in the same direction as your fingers. (See diagram below; click to enlarge.)
Illustration showing right-hand rule for determining direction of electric current.

Note that what actually moves in the wire are electrons flowing from the negative side of the battery to the positive side. Electrical engineers and scientists think of  “current” as a flow of positive charges that produces the same effect as that produced by the flow of negative charges in the opposite direction.



Related Snacks

A science activity that makes the patterns of a magnetic field visible
Magnetic Lines of Force

Iron filings trace out magnetic field lines in three dimensions.

Science activity that explores magnetic lines of force
Magnetic Shielding

Magnetic lines stop here.

Science activity that explores an electromagnet
Magnetic Suction

Ding dong! This investigation shows how your doorbell works.


Related Exhibits

Circles of Magnetism
Circles of Magnetism

Electricity moving in a wire makes a circular magnetic field.



Creative Commons License



This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Attribution: Exploratorium Teacher Institute

  • Education
    • Teacher Institute
    • Tools for Teaching and Learning
      • Science Snacks
        • Browse by Subject
        • Special Collections
        • Science Snacks A-Z
        • NGSS Planning Tools
        • Frequently Asked Questions



Connect with us!



  •   Sign up for our educator newsletter

  •   Follow #ExploEDU

  •   Teacher Institute YouTube

  •   Teacher Institute Facebook

  •  teacherinstitute @exploratorium.edu

Exploratorium
Visit
Join
Give

Pier 15
(Embarcadero at Green Street)
San Francisco, CA 94111
415.528.4444

Contact Us

  • Plan Your Visit
  • Calendar
  • Buy Tickets
  • Getting Here
  • Store
  • Event Rentals
  • About Us
  • Become a Member
  • Donate
  • Jobs
  • Volunteer
  • Press Office
  • Land Acknowledgment

Get at-home activities and learning tools delivered straight to your inbox

The Exploratorium is a 501(c)(3) nonprofit organization. Our tax ID #: 94-1696494
© 2023 Exploratorium | Terms of Service | Privacy Policy | Your California Privacy Rights |