1. Lesson 3 key concepts

2. Light is invisible unless detected (example: Flashlight on wall)1.
Light is invisible unless detected (example: Flashlight on wall)

3. 2.
Detection of light requires its interception by matter. (example: dust and mist)

4. Light travels in straight lines.3.
Light travels in straight lines.

5. Light spreads out as it moves from a light source.4.
Light spreads out as it moves from a light source.

6. 5.
Light moves very fast. (varies depending on material through which it travels)

7. 6.
Diffraction: Bending of a wave as it moves from one medium into another medium.

8. Vacuum
3.0 X 108 m/s

9. Water
2.25 X 108 m/s

10. Glass
2.00 X 108 m/s