ABSTRACT

This chapter discusses the nature of photons and electrons in order to gain familiarity with their overall properties. Photons and electrons appear to behave either as particles or as waves to people only because of the limitations of the modes of thought. The chapter discusses the matters of momentum, energy, and power in the light wave. The fact that a light wave carries momentum and energy is evident from a number of its mechanical effects, such as the forced rotation of a conducting vane in a vacuum when one side is exposed to light. The particulate view of light necessitates the representation of a light flux as a stream of photons "guided" by an electromagnetic wave. This immediately raises the question of the arrival statistics of the stream. To fix ideas, the chapter considers the rate at which photons arrive at the sensitive surface of a photodetector.