Physics 1230: Light and Color Ivan I. Smalyukh, InstructorCourse BusinessPhysics 1230: Light and Color Ivan I. SmalyukhSlide 4Slide 5Slide 6Slide 7Slide 8Slide 9What will be tested in this class? How can I get a good grade?Survey to be answered by clickersSlide 12Scientific notation and metric systemClicker questionSlide 15Intro and Chapter 1 ContinuedSlide 17Slide 18Slide 19Rays (a single beam of light, for example)Light rays are invisible unless they enter directly into our eye or are scattered by smoke, fog or some object into your eye!Rays bounce when they reflect off a mirror or shiny surfaceSlide 23Slide 24WavesSlide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Period and frequency of a wave and relation to wavelength and speedSlide 36What would happen if sound waves could propagate through empty space???Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45We see color when waves of different wavelengths enter enter our eyes!Clicker questionsSlide 48What happens when two or more waves with different wavelengths reach your eye?What is white light?Light at wavelengths which we see as colors are part of a wider family of electro- magnetic wavesIt's a good idea to remember some rough wavelengths associated with colorsWhat happens when those other electromagnetic waves enter our eyes?Slide 54Slide 55Slide 56Slide 57Slide 58How much time it takes for the wave to travel distance of 9000 km?How does an ordinary incandescent light bulb work?Neon lights have atoms with resonances at special colors inside. They use alternating (AC) household current (Demo)When rays come out in various different directions from an object or objects, the wavefront is defined as a curve or surface perpendicular to all the raysHow are wave wiggles related to rays?HW #1 is due todayPhysics 1230: Light and ColorIvan I. Smalyukh, InstructorOffice: Gamow Tower, F-521Email: [email protected]: 303-492-7277Lectures: Tuesdays & Thursdays, 3:30 PM - 4:45 PMOffice hours: Mondays & Wednesdays, 3 PM - 4 PMGrading Assistants:Jian Yao, Yiheng Lin, Hao SongLecturesHomeworksExamsHands-on experienceDemonstrationsPeer Instruction (with extra credit)Fun2•WebsiteWebsitehttp://www.colorado.edu/physics/phys1230/http://www.colorado.edu/physics/phys1230/phys1230_fa09/phys1230_fa09/•SyllabusSyllabus–Science of light and colorScience of light and color–HW assignments, reading and exam datesHW assignments, reading and exam dates•Course infoCourse info–GradesGrades–Clicker technologyClicker technology•Another kind of invisible waveAnother kind of invisible wave•WebsiteWebsitehttp://www.colorado.edu/physics/phys1230/http://www.colorado.edu/physics/phys1230/phys1230_fa09/phys1230_fa09/•SyllabusSyllabus–Science of light and colorScience of light and color–HW assignments, reading and exam datesHW assignments, reading and exam dates•Course infoCourse info–GradesGrades–Clicker technologyClicker technology•Another kind of invisible waveAnother kind of invisible waveCourse BusinessPhysics 1230: Light and ColorIvan I. Smalyukh•What is "science"?•Why is learning science like learning a foreign language?–Words have new and precise meanings–Wave, image, ray, lens, white, exposure, file, see, reflection, refraction, dispersion, particle–What does it mean for the "sun to set?" Is there really global warming? How could complex and magnificent creatures like us have evolved from lower species? •We all have scientific curiosity:•Why the sky is blue?•What is rainbow?•What is sunset?•How my laptop display works?•We all have scientific curiosity:•Why the sky is blue?•What is rainbow?•What is sunset?•How my laptop display works?Ornithoptera chimaera chimaeraOrnithoptera chimaera chimaera Ornithoptera goliath supremus, f. titanOrnithoptera goliath supremus, f. titan Ornithoptera priamus urvillianusOrnithoptera priamus urvillianus Papilio blumei blumeiPapilio blumei blumeiWhat will be tested in this class? How can I get a good grade?Ability to: Memorize new facts and definitions "Understand" new concepts at a minimal level Deeper understanding: Be able to figure out new things using concepts Percent of grade: 25% 25% 50% (only 15% uses math) HW#1 due next ThursdaySurvey to be answered by clickers1. What is your background for light and color? Choose the one which best describes your science backgrounda) I have had no physics in high school or collegeb) I have had physics in high school but not in collegec) I have taken a physics course OR a psychology course at the college leveld) I have taken more than one physics or psychology courses (high school and/or college level)e) I am a science majorSurvey to be answered by clickers2. Why did you take this course? Give the answer which best describes your reason.a) Because of requirements by the universityb) Because it was recommended to mec) Because it looked easyd) Because it looked interestinge) I don't know whyScientific notation and metric system•Powers of 10 give a shorthand notation for very large numbers.•103 = 1000•102 = 100•10 1 = 10•100 = 1•Or very small numbers•10-1 = 0.1•10-2 = 0.01•10-3 = 0.001•Scientists don't use feet or miles to indicate distances•They use–meters (m)•1 meter = 39.4 inches–kilometers (km)•1 km = 1000 m = 0.625 mi–centimeters (cm)•1 cm = 10-2 m = 0.394 inches–millimeters (mm)• 1 mm = 10-3 m–nanometers (nm) • 1 nm = 10-9 mClicker question•What Lottery Prize you prefer?a) $ 103b) $ 10-8c) $ 107d) $ 100e) $ 10-18•wavelength = 500 nm = 5 x 102 x10-9 m = 5 x 10-7 m•Hence 1 m = wavelength/(5 x 10-7) = 107/5 wavelengths =2 million wavelengths•Since 1 cm is 1/100 of a meter there are 2 x 106/100 = 20,000 wavelengths in a cmClicker question•The wavelength of green light is around 500 nm. How many wavelengths of green light fit into one cm (or a fingertip)?a) 20 thousandb) 50 thousandc) Two milliond) Two billione) 5 billion•500 nm = 5 x 102 x10-9 m = 5 x 10-7 m•1 cm = 10-2 m;•Hence, 10-2 /(5 x 10-7) = 20,000 wavelengths in a cmIntro and Chapter 1 Continued•Light belongs to a family of waves called electromagnetic (EM) waves (Physics 2000)–Other waves: rope waves, water waves, sound waves, etc.•Sometimes EM waves are called EM radiation–Radio waves–Radar and similar waves•microwaves•cell phone waves–Infrared or heat waves–Ultra-violet (suntan) waves–X-rays–Gamma rays•EM waves are