8A70.10 - Planetary Magnetism

Code Number:
Demo Title:
Planetary Magnetism
Magnetic Forces & Fields
Area of Study:
Electricity & Magnetism
Overhead Magnets, Iron Filings, Iron Filings in Pop Bottles with Inserted Test Tube, Neodymium Magnets, and Dip Needles.

Place the magnets attached to the Plexiglas on the overhead and sprinkle on the iron filings.  Observe the magnetic field lines.

3-D magnetic field lines may observed with the pop bottle arrangement.

CAUTION: Do not drop the magnets into the test tube as the bottom will break out.

Slide the magnets gently into the test tube.  These magnets may be removed from the apparatus after demonstration with the use of the small metal rods.

Align the dip needle with the north/south magnetic poles of the Earth.  For our location the dip needles should have an angle of approximately 72 or 73 degrees from the horizontal.

  • Jeanie I. Watt, Bradley J. Roth, "An Elementary Model of the Earth's Magnetic Field", TPT, Vol. 45, #3, March 2007, p. 168.
  • Albert A. Bartlett, "The Earth's Magnetic Field", TPT, Vol. 40, #8, Nov. 2002, p. 462.
  • Ray Ladbury, "Geodynamo Turns Toward a Stable Magnetic Field", Physics Today, Vol. 49, #1, Jan. 1996, p. 17.
  • J. E. Frederickson, "Magnetic field of earth and magnetic dipole moment--and experiment", AJP, Vol. 43, #2, Feb. 1975, p. 186.
  • C. T. Russell, R. J. Strangeway, C. Zhao, B. J. Anderson, W. Baumjohann, K. R. Bromund, D. Fischer, L. Kepko, G. Le, W. Magnes, R. Nakamura, F. Plaschke, J. A. Slavin, R. B. Torbert, T. E. Moore, W. R. Paterson, C. J. Pollock, and J. L. Burch, "Structure, Force Balance, and Topology of Earth’s Magnetopause", Science, Vol. 356, #6341, June 2017, p. 960.
  • Isaac Asimov, "From Pole to Pole", Fantasy and Science Fiction Magazine, p. 142 - 151.
  • Isaac Asimov, "Iron, Cold Iron", Fantasy and Science Fiction Magazine, p. 109 - 118.
  • Kathy A. Svitil, "Mighty Microbes", Discover Magazine, Feb. 1994, p. 25.
  • James Cunningham and Norman Herr, "8.3.7. Geomagnetism", Hands-On Physics Activities with Real Life Applications, 1994, p. 607 - 608, 613 - 614.
  • "Which Way is North?", Facts and Fallacies - Readers Digest, p. 17 - 18.
  • John G. Cramer, "Falling Through to Pellucidar", Analog Science Fiction/Science Fact Magazine, p. 104 - 108.
  • Janice VanCleave, "14. Mapping", Janice VanCleave's Magnets, p. 56 - 59.
  • Jennifer Leman, "The Magnetic North Pole Is Racing Toward Russia", Popular Mechanics, Sept. / Oct. 2020, p. 28.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.