announcements 10/28/11 prayer exam 2 going on… slinkies: please turn in and cross your name off...
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Announcements 10/28/11 Prayer Exam 2 going on… Slinkies: Please turn in and cross your name off the
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SpeedBump
Reading Quiz What is a “wave front”?
a. The crest of the wave, repeated every b. The complex phase of a wavec. The first part of the wave to reach an
objectd. The reflection of a wave off of a surfacee. The students at the football game who
start “The Wave”
Reading Quiz
What do we call the phenomena which makes fiber optics possible?
a. Brewster’s Lawb. Equivalence Theoremc. Fermat’s Principled. Superluminal Energy Transporte. Total Internal Reflection
Demo Stokes computer demo: (5:00)
http://stokes.byu.edu/refract_script_flash.html
Thought question
If you have a -0.3 dB change, the final intensity is what fraction of the initial intensity? (You’ll need your calculator.)
a. 78%b. 83%c. 88%d. 93%e. 98%
-0.3 dB 93.3%-0.2 dB 95.5%-0.1 dB 97.7%
Reading Quiz
When we think of all the points on a wave front as little sources of secondary waves in order to calculate what the wave front will look like after propagating some distance, we are using the idea known as...
a. the Equivalence theoremb. Huygen’s Principlec. Fermat’s Principled. Newton’s first law of opticse. the Wavelet theorem
Huygen’s Principle
Each wavefront serves as source of spherical waves HW 26-5 (extra credit):
a. “Stare at the picture until you can visualize that the green lines tangent to the circles connect matching wavefronts.”
b. Construct an accurate picture like this for a specific situation, show graphically that it gives you Snell’s law
Image credit: Wikipedia
Huygen’s Principle, cont.
A wave hits the two slits Each slit (infinitely narrow) becomes source of
spherical waves The waves from those two sources interfere with
each other
Image credit: Wikipediahttp://en.wikipedia.org/wiki/
Double-slit_experiment
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