Monk and Osborne ("Sci Educ" 81:405-424, 1997) provide a rigorous justification for why history and philosophy of science should be incorporated as an integral component of instruction and a model for how history of science should be used to promote learning of and about science. In the following essay we critique how history of science is used on…

In 1889, German biologist August Weissmann showed that mice whose tails are cut off do not produce short-tailed offspring. It was a step forward for science, but a step backward for civilization. Weissmann's discovery was good for science because, contrary to what many scientists had believed, acquired characteristics are not, of course,…

Le Chatelier's principle states that the further addition of a particular component will cause the reaction to shift in the direction that reduces the total number of moles of the system. However, the addition of one reactant [N[subscript 2]] as in the ammonia synthesis reaction may cause the reaction to proceed in a direction that produces more…

A proper presentation of scientific discoveries may allow science teachers to eliminate certain myths about the nature of science, which originate from an uncertainty among scholars about what constitutes a discovery. It is shown that a disagreement on this matter originates from a confusion of the act of discovery with response to it. It is…

The notions of "idealisation" and "approximation" are strongly linked to the question of "how our theories represent the phenomena in their scope". Although there is no consensus amongst Philosophers on the nature of the process of idealisation and how it affects theoretical representation, at the level of science education much can be gained from…

The laboratory exercise described in this paper is based on a well-known qualitative demonstration of Curie temperature. A long ferromagnetic wire, in the form of a spiral, is attracted to a strong permanent magnet placed near its midpoint (see Fig. 1). The temperature of the wire is increased by passing a current through it. When the temperature…

Although the resolution to the wave-particle paradox has been known for 80 years, it is seldom presented. Briefly, the resolution is that material particles and photons are the quanta of extended spatially continuous but energetically quantized fields. But because the resolution resides in quantum field theory and is not usually spelled out in…

Too often, students in introductory courses are left with the impression that Einstein's special theory of relativity comes into play only when the relative speed of two objects is an appreciable fraction of the speed of light ("c"). In fact, relativistic length contraction, along with Coulomb's law, accounts quantitatively for the force on a…

As the topic of relativity is developed in a first-year physics class, there seems to be a tendency to move as quickly as possible to the fascinating ideas set forth in Einstein's special theory of relativity. In this paper we linger a little with the Galilean side of relativity and discuss an intriguing problem and its solution to illustrate a…

Teachers have been building mystery circuits or so-called "black box circuits" to use as a demonstration with their students for years. This paper presents an easy way to make simple mystery circuits using inexpensive light fixtures (see Fig. 1) available at almost any home improvement store. In a black box circuit, only the lightbulbs are visible…

Newton's third law is often misunderstood by students and even their professors, as has already been pointed out in the literature. Application of the law in the context of electromagnetism can be especially problematic, because the idea that the forces of "action" and "reaction" are equal and opposite independent of the medium through which they…

The following idealized problem is intended to illustrate some basic thermodynamic concepts involved in kinetic friction. A block of mass m is sliding on top of a frictional, flat-topped table of mass M. The table is magnetically levitated, so that it can move without thermal contact and friction across a horizontal floor. The table is initially…

The pages of "The Physics Teacher" have featured several clever designs for homemade diffraction gratings using a variety of materials--cloth, lithographic film, wire, compact discs, parts of aerosol spray cans, and pseudoliquids and pseudosolids. A different and inexpensive method I use to make low-resolution diffraction gratings takes advantage…

Ordinarily, opening a door by pulling on the knob or handle causes a net torque on the door, and hence an angular acceleration, about a "vertical" axis. However, it may be that the top or bottom of the door sticks to the door frame; this horizontal force perpendicular to the plane of the door causes a torque on the door about a "horizontal" axis.…

In electric or mixed electric-mechanic systems, the distinction between potential and kinetic energy is not as clear as in purely mechanical systems. A solution for the motion of an inductively loaded rail generator is presented. In this case, the magnetic field energy (1/2)Li[superscript 2] can be written "formally" in terms of a potential…