Models of Light: Light as a Particle
Seventeenth-century physicist Isaac Newton was one of the first scientists to theorize that light consists of a stream of particles. Modern physicists have demonstrated that the energy in any electromagnetic field is made up of discrete, massless energy packets—called photons.
Watch this video, which provides evidence that light is not just waves but also particles. As you watch, consider which model of light is more intuitive for you.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Video: Pushing a Spacecraft with Light? | Physics Girl
Take Notes
- How does the space sail help visualize and provide evidence that light exists as particles?
- Which model of light did you decide is more intuitive for you? Why do you think that is? How might your students respond to the two different representations?
