Welcome to PH 103 Dr. Cecilia Vogel Lecture 1

Class structure  Syllabus  oc oc  Materials  Text: Giancoli, “Physics”  Calculator  Quizdom remote  WebAssign registration  online or bookstore

You don’t have to…  read the book before class  come to class  ask questions in class  understand the assignments you get help with … unless you want to do well in the class!

Light  Electromagnetic wave  oscillating electric and magnetic fields  -- not moving matter!  wave moves at speed v  wavelength = distance between repeats  frequency = # oscillations per second f =v f (speed c=3X10 8 m/s in vacuum)

How fast?  Frequency of wave  how fast is it oscillating?  depends on the thing that’s creating the oscillations  Speed of wave  how fast is it getting from point A to point B?  depends on the properties of the thing the wave is traveling through

MEMORIZE EM SPECTRUM  Visible:  Longer:  Shorter: = nm Infrared, microwave, radio UV, X-rays, gamma violet thru red

Speed of light  Speed of light is c=3X10 8 m/s, only in vacuum  Speed in other materials  is slower than vacuum  index of refraction, n  tells how much slower  in material, v=c/n  n=1 vacuum, n= air,  n=1.33 water, n=2.42 diamond

Material and Wavelength  Speed in other materials  is slower than vacuum  If light passes from vacuum to material  frequency is unchanged  but speed changes – what happens to   so wavelength decreases when speed decreases  in material,  v=c/n  =  /n