Mathematics 309 - Spring 2003

2. Rays or waves?

• What is light? In this course, light will be waves of energy distributed in space. (We'll not look at photons and quantum mechanics, as far as I can see.) However, light seems to travel along rays, perpendicular to the waves. It comes from somewhere, doesn't it? How is that? Psychological reasons, physical reasons. In any event, much of the time in this course we'll treat light as if it traveled along rays.
• What is colour? Energy has different frequencies. The colour sensitive parts of the eye act as filters.
• What is polarization? The energy has transverse direction.
• Refraction. From wave motion. Wave velocity. Rays bend.