1. Sources of Light

2. Luminous Body – An object that emits light waves.

3. Illuminated body – an object that reflects light

4. Types of Reflection Specular (Regular) Reflection Diffuse (Irregular) Reflection The angle in which the light strikes the surface of a material with respect to the normal is the same angle it leaves the material.

5. Speed of Light

6. Danish Astronomer Ole Roemer (1644-1710) was the first to determine that the speed of light is finite. Sun Jupiter Sun Earth Io Earth Io Jupiter

7. Albert Michelson (1852-1931) was the first Physicist to accurately determine the speed of light. d=35 km θ v=2πr/T=2πrf v=θ/t  t=θ/v r v=2d/t

8. The speed of light was determined by Michelson to be 2.997996 ±.00004x10 8 m/s The speed of light is now accepted as 2.99792458x10 8 m/s in a vacuum. 3.00x10 8 m/s can be used for calculations. c=3.00x10 8 m/s The speed of light is considered as the speed limit for matter in the universe. v=fλ  c=fλ

9. Speed of Light in a Medium c=nv c=3.00x10 8 m/s in a vacuum. c=the speed of light in a vacuum n: index of refraction (optical density) of the medium v: speed of light in the medium Index of refraction: The ratio of the speed of light in a vacuum to a medium. The index of refraction is a relative measure of how much light bends in traveling from one medium to another. The index of refraction, n ranges from 1.00 in a vacuum to 2.42 (higher index of refraction values are possible) Index of refraction value examples: 1.00 vacuum, 1.0003 air (1.00), 1.33 water, 1.34 ice, 1.52 crown glass, 1.54 flint glass, 2.30 cubic zirconia, 2.42 diamond. The larger the index of refraction, the slower light travels in that medium.