In this lesson our instructor talks about light. First, he discusses the speed of light, light speed, and medium. Then he talks about electromagnetic spectrum and wave classifications. Three complete example problems round up this lesson.
Light is extremely fast. In a vacuum, light travels at
c=299 792 458
Depending on the material light is traveling through, its speed will change. Light travels through air close enough to c that we can use that value when working on problems.
Since light moves so fast, we can talk about very large distances using its speed as a reference point:
Lightyear = c ·(1 year).
Normally waves need a medium to propagate through. This is not true of light, though. Light is able to travel without any medium (which is why the light of the sun can reach us, even though it's a wave).
The word "light" is sort of a misnomer. The visible spectrum we are used to seeing is only part of the much larger electromagnetic spectrum that makes up light.
Different kinds of electromagnetic waves have different frequencies. Higher frequencies carry more energy, lower frequencies carry less.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
This book includes a set of features such as Analyzing-Multiple-Concept Problems, Check Your Understanding, Concepts & Calculations, and Concepts at a Glance. This helps the reader to first identify the physics concepts, then associate the appropriate mathematical equations, and finally to work out an algebraic solution.