After learning how to trace the principal rays [Fig. 1(i)] through a thin lens in order to form the image in the conventional way, students sometimes ask whether it is possible to use other rays emanating from the object to form exactly the same image--for example, the two arbitrary rays shown in Fig. 1(ii). The answer is a definite yes, and this…

Describes a method of staining that makes details clear and dispenses with the time-consuming use of chemicals. The Rheinberg differential color illumination, (or optical staining) is strikingly beautiful and is especially useful with living or nonliving unstained, transparent specimens. Color photographs of sample specimens are included.…

Photography can be a useful tool for teaching biology at both the macroscopic and the microscopic levels of organization. While more complex, taking photographs of microscopic specimens is a procedure that can be performed with all students. In this article, the authors outline a general approach that can be followed to develop a specific protocol…

Explains the problem of analyzing a phase object, separating the contribution due to thickness variations and that due to refractive index variations. Discusses the design of an interferometer and some applications. Provides diagrams and pictures of holographic images. (YP)

Discusses a demonstration in which the near and far focusing distances of a student volunteer are measured and his or her glasses prescription is computed. (HM)

Described is the sequence of topics, learning activities, materials and demonstrations for the course. It is stressed that students can learn these skills in less than 30 hours of instruction. (CW)

Presents two methods for measuring the index of refraction of glass or lucite. These two methods, used in the freshman laboratory, are based on the fact that a ray of light inside a block will be refracted parallel to the surface. (HM)

This curriculum for a 1-semester or 1-year course in electronics is designed to take students from basic through advanced electronic systems. It covers several electronic areas, such as digital electronics, communication electronics, industrial process control, instrumentation, programmable controllers, and robotics. The guide contains…