Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

The author draws attention to the possibilities of introducing the concept of electromagnetic energy flow associated with the Poynting vector at an elementary stage of physics instruction. (Author/SA)

Discusses electric and magnetic forces between parallel-wire conductors and derives, in a simple fashion, order of magnitude estimates of the ratio of the likely electrostatic and electromagnetic forces for a simple parallel-wire balance. (Author/HM)

Various modes of reflection are classified and practical examples of devices, such as cat's eyes, are discussed. Typical light rays are traced through several systems, providing exercises with varying degrees of difficulty. Corner-cube retroreflectors, glass spheres, reflecting luminaries, light concentrators, parabolic reflectors, and off-set and…