hw 4

Viewed in Another Light Read from Lesson 2 of the Light Waves and Color chapter at The Physics Classroom: http://www.physicsclassroom.com/Class/light/u1212d.html http://www.physicsclassroom.com/Class/light/u1212e.html MOP Connection: Light and Color: sublevel 5 We are accustomed to viewing the world in white light. In effect, the light incident upon the objects we normally view can be simplified as a mixture of red, green and blue light (RGB). But the rules of color addition and subtraction are not limited by the restriction that white light is incident upon the object being viewed. After all, an object is often times illuminated by light other than white light. For example, theaters and concerts often illuminate the stage with red light or cyan light or any combination of two or more light colors. Determining the color appearance of such objects demands that you first identify what color(s) of incident light will be subtracted (i.e., absorbed), and then deduct the appearance of the object from those colors which are reflected. In the diagrams below, several sheets of paper are illuminated by different primary colors of light (R for red, B for blue, and G for green). Indicate what primary colors of light will be reflected. (Note that red paper is defined as paper that appears red when viewed under white light.) 9[ er) B P Cyan \:R(iigltt \’C GBLight \:R(Eitht \’ ’ \Green Paper} agtnfa (K N 3) Green Paper (RfB) \C_ga—;fe%& RG (4 RGB \{euw RGL' " _R+G» Ycllow ig : “._Light \’ “._Light \’ \Eia—"“fi{% Yellow Pape Yellow Pape ue ue ..g&] GB _3[;“_’\ RG _Red BG _Bue Light Light \ Light \’ 8 M I"Iag:_at;%k l}‘lagenta Pape A Bue qrem grccn e Different color light sources are shone on different colored sheets of paper. Consider which colors of light would reflect off the paper in order to determine the cgi()r H\;}l is observed. Light color ] Paper colo}’ Color observed Magen a. Yellow R+ Green | R+8 Green b. Magenta R48 Blue Y&'}_}‘: Blue C . Cyan Bt Red é’:i'r BlacK d. Yellow RHr Cyan | R Qr een Ma N/ Magenta R4 Green gr Black f. Cyan B¢ Magental ¢ Blye © The Physics Classroom, 2009 Page 9