Iowa Science Teachers Journal Volume 17 Number 1 Article 4 1980 The Earth's Magnetic Field Robert S. Carmichael University of Iowa Follow this and additional works at: https://scholarworks.uni.edu/istj Part of the Science and Mathematics Education Commons Let us know how access to this document benefits ouy Copyright © Copyright 1980 by the Iowa Academy of Science Recommended Citation Carmichael, Robert S. (1980) "The Earth's Magnetic Field," Iowa Science Teachers Journal: Vol. 17 : No. 1 , Article 4. Available at: https://scholarworks.uni.edu/istj/vol17/iss1/4 This Article is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Iowa Science Teachers Journal by an authorized editor of UNI ScholarWorks. For more information, please contact
[email protected]. THE EARTH'S MAGNETIC FIELD Robert S. Carniichael, Ph.D. Department of Geology University of Iowa Iowa City, Iowa 52242 Introduction "He who controls magnetism controls the world." Dick Tracy (ca. 1950's), in investigating yet another diabolical plot In the year 1600, the Englishman William Gilbert published "De Magnete", one of the first true scientific treatises. He had studied, with a compass needle, the dip and pattern of the magnetic field around a sphere of lodestone magnetite (the mineral Fe304). Further, he de duced that the Earth had a similar field, and was therefore like a giant magnet. The Earth's field is illustrated schematically in Figure 1. To a first approximation, it is like that due to a dipole, or very short magnet, near the center of the Earth.