Introduces the method of ray tracing to analyze the refraction or reflection of real or virtual images from multiple optical devices. Discusses ray-tracing techniques for locating images using convex and concave lenses or mirrors. (MDH)

Describes a theoretical development to explain the shadow patterns of an object exposed to an extended light source while held at varying distances from a screen. The theoretical model is found to be accurate in comparison with experimental results. (MDH)

Describes a homemade experimental chamber constructed to accurately measure the refractive index of a transparent liquid. (MDH)

Addresses the problem that students balk at the notion velocities do not add algebraically. Offers a geometric model to verify the algebraic formulas that calculate velocity addition. Representations include Galilean relativity, Einstein's composition of velocities, and the inverse velocity transformation. (MDH)

Describes an inexpensive spectrum projector that makes high-dispersion, high-efficiency diffraction gratings using a holographic process. Discusses classroom applications such as transmission spectra, absorption spectra, reflection characteristics of materials, color mixing, florescence and phosphorescence, and break up spectral colors. (MDH)