Loading video...
Light
- Light is extremely fast. In a vacuum, light travels at
c=299 792 458 m s≈ 3·108 m s. - 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.
Light
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.
- Intro
- The Speed of Light
- Lightspeed!
- Medium
- Electromagnetic Spectrum
- Electromagnetic Wave Classifications
- Long Radio Waves & Radio Waves
- Microwave
- Infrared and Visible Spectrum
- Ultraviolet, X-rays, and Gamma Rays
- So Much Left to Explore
- Example 1: How Much Distance is in a Light-year?
- Example 2: Electromagnetic Wave
- Example 3: Radio Station & Wavelength
































Start Learning Now
Our free lessons will get you started (Flash® 10 required).
Sign up for Educator.comGet immediate access to our entire library.
Features Overview