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Day 2: Design and Build a Magnetometer
Background Information

The magnetometer is a glorified compass. The virtue of the magnetometer is to have the students create the instrument rather than rely unthinkingly on a 'black box'. The student built magnetometers will be a primitive version of an instrument that is used on all satellites, is similar to the devices people to find 'buried treasure' and lost coins in city parks and at the beach, and is used by photographers trying to get pictures of the aurora. (See Unit Extensions.)

The piece of index card is to allow the students to label the ends of the magnet. I encourage you to use designations like "End A" and "End B". This may help the students be a little more involved in what is happening. As soon as we say "north" and "south" the students may fall into a 'the book says' answering pattern. It is suggested that you standardize the class reference system so that all class members use the same direction convention. This will aid in communication later.

The magnet must be able to swing in a full horizontal circle in response to the external magnetic field. The magnet is like the "test charge" used in electrostatics to measure electric field strength.

This version of the magnetometer is light enough to hang from the ceiling. This will allow the student to make direction maps of magnetic fields at different heights relative to various sources. The purpose of this is to help the students think of magnetic fields as 3-dimensional entities. In all most all instances, magnetic fields are drawn using a 2-dimensional or planar representation. The students will discover that the curvature of the field lines exists in all 3 dimensions.

The Practice Using the Magnetometer task can be done as homework or as an in-class investigation. If students do this at home, some class discussion time should be devoted to logistics and how to investigate the behavior under consideration.

Lesson Development/Writing: Ed Eckel
Web Design: Theresa Valentine
Last Updated: 8/15/2000