1. Getting in Light’s Way

2. Optics For the study of optics, when looking at the behaviour of light, it is very helpful to use a simplified model called the ray model of light.

3. Ray Model of Light In this model light is represented as a straight line to show the direction the light wave travels in. A ray is an imaginary line showing the direction in which light is travelling.

4. Light: Absorption, Reflection or Transmission? The type of matter in an object determines the amount of light it absorbs (takes in), reflects (bounces off), and transmits (passes through).

5. Light travels in a straight line until it strikes something. Transparent materialsTransparent Translucent materialsTranslucent Opaque materialsOpaque

6. Transparent A transparent material allows light to pass through it freely. Examples include: Air water, and window glass See the speed of light in different transparent materials: http://micro.magnet.fsu.edu/primer/java/speedo flight/index.html http://micro.magnet.fsu.edu/primer/java/speedo flight/index.html

7. Translucent A translucent material allows most light rays through, but are scattered in all directions. Examples include Frosted glass lampshades

8. Opaque An opaque material prevents any light from passing through it.

9. Reflection There are two types of reflection: 1.SpecularSpecular Reflection from a mirror-like surface, which produces an image of the surroundings. 2.DiffuseDiffuse Reflection from a rough surface, which does not produce a clear image but instead allows you to see what is on the surface.

10. Specular reflection Smooth surfaces reflect light uniformly.

11. Diffuse Reflection Rough surfaces appear to reflect light randomly.

12. Specular or diffuse reflection? Diffuse reflection allows you to be able to read print on a page. The black ink absorbs most of the incident light and does not reflect light back to your eye. White paper produces diffuse reflection and reflects the rays in all directions.

13. Other examples of specular and diffuse reflection Matte and Glossy paints Matte paints have a higher proportion of diffuse reflection resulting in lower luster. Glossy paints have a greater proportion of specular reflection resulting in a shinier appearance.

14. Matt vs. Glossy Photos

15. Questions 1. Are the following transparent, translucent or opaque? A) Very smoky air B) Waxed paper C) an ice cube 2.Give 2 new examples of transparent materials, translucent materials and opaque materials. 3. Describe how you know that light travels in a straight line.