Hooke's law for springs, stating that the force needed to extend or compress a spring by some distance is proportional to that distance, is a topic covered by almost all introductory physics courses at both school and university levels. In this article we present a much more efficient and intuitive approach, compared to the traditional method, for…

Quantum physics is the basis for many technologies that are a fundamental part of our daily lives (e.g., lasers) or that may become so in the future (e.g., quantum cryptography and quantum computing). Because of this, quantum physics is now a central aspect of many countries' secondary school curricula. In this article, we present the design and…

Reviews the concepts behind atmospheric optical phenomena such as rainbows and anticrepuscular rays. Describes the experience of observing these two phenomena simultaneously and calculates the probability of that observation. (JRH)

Presents a demonstration that uses insulated conductors and hairs clipped from rabbit fur to help students visualize the electric field in three dimensions and motivate them to try their own variations. (JRH)

Attempts to quantify the subjective sensation of brightness of the spot projected by a helium-neon laser and compares this with conventional sources of light. Provides an exercise in using the blackbody radiation formulas. (JRH)

Presents a derivation of Kepler's Third Law for elliptical orbits that requires students to have a knowledge of angular momentum and conservation of energy. (JRH)

Discusses the working of a dial lock using a scaled-up model. (JRH)

Describes the construction of lithographic gratings and Young's double slits by a contact print method that does not require any special skill or equipment. (JRH)

Describes the laws of physics that allow a motorcycle rider to control the flight of a motorcycle over obstacles in a motocross track. (JRH)

Describes the construction of a bed of nails that can be used to illustrate the relationship between force and pressure. (JRH)

Reports that environmental radioactivity levels vary with temperature and precipitation and these effects are due to radon. Discusses the measurement of this environmental radioactivity and the theory behind it. (JRH)

Describes the physics behind the shadows cast on a stream bed by subtle dimples on the surface of transparent water. (JRH)

Describes methods used to investigate the working of 3-D glasses available with comic books. Reports that the glasses are produced using methods of binary optics and that a prism effect, as well as diffraction grating, is incorporated in the design. (JRH)

Explains the theory behind the working of Scotchlite, a retrodirective material used for coating automotive license plates, and the Ensure Imaging System that allows law enforcement officers to verify the authenticity of the plate. (JRH)

Presents activities to determine whether it is better to test dry cells with an ammeter than with a voltmeter and how best to test alkaline batteries. Discusses classification of disposable testers as instruments. Concludes that a laboratory voltmeter gives a good indication of the condition of an alkaline cell while carbon batteries are best…