As often happens, a lot of physics can come out of a toy. What we found interesting is the observation of the magnetic field produced by different configurations built with GEOMAG.™1 This toy provides small magnetic bars and steel spheres to play with. Amusing 3-D structures can be built; nevertheless, this possibility is not so obvious. Indeed, in order to build a solid figure it is necessary to join at least three bars to a sphere, and therefore at least two of the poles attached to the sphere present the same polarity, but opposite poles should attract and similar poles should repel. To understand what happens, it is helpful to consider simpler configurations.
REFERENCES
1.
Many toy firms are now selling products similar to GEOMAG™; http://www.geomagsa.com.
2.
Each system of bars and spheres has been put underneath a glass, on the surface of which iron filings have been spread.
3.
By “magnetic circuit” we mean a closed configuration of successive ferromagnetic elements in which the magnetic field is almost completely confined. Sometimes the circuit can be interrupted by small openings (“gaps”). The magnetic circuits are widely used in electrotechnics (for example, electromagnets and transformers).
This content is only available via PDF.
© 2007 American Association of Physics Teachers.
2007
American Association of Physics Teachers
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.
