# Browsing the Journals

Carl E. Mungan
• In the May 2009 issue of The Physics Teacher, Vincent Toal and Emilia Mihaylova present a two-page article entitled "Double-Glazing Interferometry." They explain how one can easily see white-light fringes by looking at the full moon against a black night sky through a double-paned window at an angle. A secondary image of the moon with interference fringes appears beside the moon. I found it also worked to look at a large street lamp, so there's no need to wait for a full moon. I must admit I have often seen such secondary images previously through my house windows at night but had not taken any notice of them, a demonstration of the fact that "discovery activities" need to be guided to be truly effective.

• An article entitled "On the stability of electrostatic orbits" in the May 2009 issue of American Journal of Physics discusses the stability of two charged conducting spheres orbiting each other in free space. Effects of charge polarization and dependence on the orbital angular momentum are analyzed. The first two references in the paper are to the actual demonstrations of such orbits using graphite-coated styrofoam spheres aboard the "Vomit Comet" aircraft by undergraduate students.

• In the featured paper "A simple demonstration of a general rule for the variation of magnetic field with distance" in the May 2009 issue of Physics Education, a Japanese geophysicist discusses a simple method to measure the variation in magnitude of the field with distance along the axis of a small permanent magnet using only an ordinary compass. The idea is to position the magnet's axis to be perpendicular to earth's magnetic field so that the tangent of the compass needle's deflection angle gives the ratio of the magnet's field strength to that of the earth. The connection to the magnet's dipole moment is analyzed.

• In the featured paper "A simple demonstration of a general rule for the variation of magnetic field with distance" in the May 2009 issue of Physics Education, a Japanese geophysicist discusses a simple method to measure the variation in magnitude of the field with distance along the axis of a small permanent magnet using only an ordinary compass. The idea is to position the magnet's axis to be perpendicular to earth's magnetic field so that the tangent of the compass needle's deflection angle gives the ratio of the magnet's field strength to that of the earth. The connection to the magnet's dipole moment is analyzed.

• "A simple derivation of Kepler's laws without solving differential equations" in the May 2009 issue of European Journal of Physics presents an elegant geometrical derivation of Kepler's three laws where the force of gravity is approximated as a succession of impulses (so that the orbit is an elliptically shaped polygon). The key step is to introduce the Runge-Lenz ("eccentricity") vector to obtain the equation of an ellipse in polar coordinates.

• A fairly new journal, featuring pedagogical physics articles in both English and Spanish, is the Latin-American Journal of Physics Education (freely available on the web), published in January, May, and September. For example, the May 2009 issue includes articles about laboratory determinations of Malus's law, properties of a pendulum, and Planck's constant.

• The International Commission on Physics Education puts out a Newsletter twice a year. As might be expected, it features articles and advertises conferences that promote physics education in different geographical areas of the world.

• From time to time, the Journal of Chemical Education has articles of interest to physics educators, particularly in the areas of thermodynamics and statistical mechanics. A notable example is the January 2009 issue whose "Research: Science and Education" section focuses on articles discussing entropy, the Clausius-Clapeyron equation, and the virial expansion.

Carl Mungan is a member of the physics faculty at the U.S. Naval Academy in Annapolis, MD.
Disclaimer - The articles and opinion pieces found in this issue of the APS Forum on Education Newsletter are not peer refereed and represent solely the views of the authors and not necessarily the views of APS.