UW-Madison PHYSICS 109 - Light, Color, and Reflection (3 pages)

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PHYSICS 109 1nd Edition Lecture 1 Outline of Current Lecture I Light and Color II Reflection a Specular Reflection b Diffuse Reflection III Reflection from a mirror Current Lecture I II Light and Color a How we perceive light depends on i The nature of light ii How our eyes work iii How our brain processes the signal sent from our eyes b Complementary Colors if you add complementary colors you get white i Cyan and red ii Blue and yellow iii Green and Magenta 1 After staring at a color for a long time your senses get tired and stop responding to the color and when you look at a white screen you see the commentary color c The wave length for light is much smaller than the wave length for sound i The physics behind the two are the same Reflection the change in direction of a wave front at an interface between two different media so that the wave front returns into the medium from which it originated a There are two types of reflection i Specular reflection reflection off a smooth surface 1 Looking in a mirror smooth well defined surface 2 The normal is a line perpendicular to the surface ii Diffuse Reflection reflection off a rough surface These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute b Reflection from a Mirror Specular Reflection i The law of specular reflection states that the angle of incidence is equal to the angle of reflection i r ii The image that reflects from a mirror is virtual not real because there is not light where it looks like the object is 1 There are no real rays of light that emerge from the image only artificial extensions of the reflected rays originate from the image 2 You can only see the virtual image is you are on the same side of the object iii The distance from the object to the mirror is equal to the distance from the mirror to the image 1 If you are 6ft tall you need a mirror that is 3 feet tall to be able to see yourself from head to