Many secondary/college textbook authors define current explicitly or implicitly, by the diagrams, in terms of negative-charge motion. Discusses several reasons why the "conventional current" direction is preferred. (JN)

Reviews EduTech mechanic simulations of vertical fall with/without air resistance, hunter-monkey paradox, planetary motion for Apple II. The self-contained programs are designed for teacher use during demonstrations or as supplementary tutorial material. Indicates simulations are well done/useful but too much unnecessary (although informative)…

Discusses the basics of inexpensive modular synthesizers (which demonstrate various principles of sound). Topics considered include: oscillators and musical range; oscillator waveforms and characteristics; synthesizing simple musical sounds; and modulation and sweeping filter effects. Suggestions for purchasing or building synthesizer components…

In response to conventional rocket demands on fuel supplies, electromagnetic launches were developed to give payloads high velocity using a stationary energy source. Several orbital mechanics problems are solved including a simple problem (radial launch with no rotation) and a complex problem involving air resistance and gravity. (DH)

Suggests using a "bed of nails" (array of nails on a board) as a resistance demonstration where steel balls pass through the lattice of nails like electrons through metal. Although weaknesses of Drude's electrical conduction model are noted, the activity is recommended since it clearly illustrates drift velocity. (DH)

Discusses a problem (on page 523 of "College Physics," by Sears, Zemansky, and Young, published by Addison-Wesley, 1980) concerning light bulbs and resistance. Shows why the assumption of constant resistance is unrealistic and provides guidelines for revision. (DH)

The moving pattern that appears on an oscilloscope screen is used to illustrate two kinds of wave motion and the relationship between them. Suggestions are presented for measuring wavelength, frequency, phase shift, and phase velocity in this college-level laboratory exercise. (DH)

Provides a simple routine which allows first-year physics students to use programmable calculators to solve otherwise complex electrostatic problems. These problems involve finding electrostatic potential and electric field on the axis of a uniformly charged ring. Modest programing skills are required of students. (DH)

Outlines a simple method which shows the relation between work done in accelerating a mass and the resulting velocity of the mass. Equipment used includes a rubber ball, ramp of lumber, graph-chart, stopwatch, and hand calculator. (DH)

Students are challenged to investigate a simple electric motor and to build their own model from a battery, wood block, clips, enameled copper wire, bare wire, and sandpaper. Through trial and error, several discoveries are made, including a substitute commutator and use of a radio to detect motor armature contact changes. (DH)

Explains: (1) use of piezoelectric film (connected to power supply and oscilloscope) to reveal force-versus-time curves of bouncing balls; (2) use of bound wood splints or meter sticks to illustrate tree or tower stability; and (3) apparatus of co-axial discs with connected linking rods and suspended bobs to simulate waves. (DH)

Discusses the drafting of lines of force and equipotentials in static potential fields, examining the general properties of equipotentials and field lines, diagrams from the literature, and the field of equal charges of opposite sign. Examples used are from both American and European textbooks. (JN)

Presents information on the moment of inertia of a tennis racket about its principal axes. This information (not available from conventional sources) is useful since it influences how the racket plays and how the racket feels when it is swung. In addition, measurements of motion can be easily made by undergraduate students. (JN)

Describes how to record and study two-dimensional collisions using video-recording equipment. These techniques have been used by students in a calculus-based physics laboratory for such experiments as the analysis of conservation of momentum on the airtable. (JN)

Background information and procedures are provided for an optics experiment related to diffraction order asymmetry. (JN)