The Munsell Color Wheel   Color Wheels Such systems were devised to meet the demands of an expanding economy that needed precise color notation. The industrial economy included more fabrics, dyes, etc., than ever before. Such systems use a notation of Letters & Numbers, seen on the dial at left, in order to ensure accuracy. A Variety of Colorwheels at FeedBlitz Newton's Color Wheel at University of Virginia Origins of the Color Wheel at Dimensions of Color     Review of the Visible Spectrum This diagram shows the small area our visible spectrum occupies within the electromagnetic spectrum.   The Electromagnetic and Visible Spectra at The Physics Classroom Additive Color Theory This picture clearly illustrates the process of matter absorbing some light rays & reflecting others   Additive Color at University of California, Santa Barbara   Introduction to the Electromagnetic Spectrum: Discovery of infrared (1800 by Sir Frederick William Herschel) and ultraviolet rays (1801 by Johann Ritter) Discovery of Infrared at The Infrared Processing and Analysis Center Johann Wilhelm Ritter and UV Rays at Universal Design Consortium William Herschel at Space.com     Introduction to the Kelvin Scale (Lord Kelvin, 1848) concept of 'absolute zero'; explanation of black-box radiation. The Kelvin system of light measurement, based upon the light that would be emitted by a "black body " heated to various temperatures. Used in the physical sciences as well as photography to indicate color temperature.   Kelvin Scale at School of Digital Photography Black Body Radiation at Georgia State University Lord Kelvin at The Scottish Science Hall of Fame   The Speed of Light Roemeran Galileo   1610 - Galileo discovered that what were previously thought to be stars were actually moons of Jupiter - proving that earth & it's moon were not the only "planetary system". 1676 - The eclipse of Jupiter and its moon Io gave Danish astronomer Olaus Roemeran (Ole Rømer; also Roemer) an opportunity to estimate the speed of light. His observation was that the same eclipse was seen later or sooner, depending on earth's proximity to Jupiter. This demonstrated that light had a finite speed. Rømer had measured celestial angles in order to use triangulation to determine an estimate of the distance between Earth and Jupiter. Accounting for the time discrepancy in observation of the same phenomenon, based on the distance between the two points, he was able to provide the speed of 186,000 miles per second, an incredibly close calculation. Galileo and The Moons of Jupiter at Rice University | The Moons of Jupiter at PHYS.org | Galileo at Stanford University Ole Rømer at The Museum of Natural History | Rømer's Determination of the Speed of Light at Wikipedia     "Newton's Rings" "When a convex lens is placed on a flat glass plate, light is reflected by the plate & by the lower surface of the lens. The two groups of rays interfere with each other to produce 'Newton's Rings.' These are named after Sir Isaac Newton (1642-1727), who first investigated this effect" - David Burnie Time-Life Books Description of how "interference" can cause "iridescence" and why the wave nature of light creates this effect, based on the relationship of the wave length of light rays and correspondingly tiny spaces between matter, such as between two pieces of touching glass (where the colors produced are called "Newton's Rings") or in between the ridges of a peacocks feather:   Here, due to their microscopic spacing, tiny "rods" of the feather create "interference" with the light rays It is actually a reverberation effect, similar to the breaking of waves upon each other at different angles. Newton's Rings at: City Collegiate | The University of Adelaide | School Physics Isaac Newton at: The Isaac Newton Institute for Mathematical Studies | University of Virginia | Virginia Commonwealth University: Principia | Optiks home back next lecture contents top