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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”

Credit: next several slides from Dr. Durfee

Law of reflection illustrated

Law of reflection illustrated

Law of reflection illustrated

Law of reflection illustrated

Law of reflection illustrated

Law of reflection illustrated

Snell’s Law illustrated

Snell’s Law illustrated

Snell’s Law illustrated

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

Total Internal Reflection TIR: the equation

Demos Blackboard optics TIR in water soluble oil Laser captured in stream of water Fiber Optics

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

Spherical WavesSpherical Waves

Credit: the next few slides are from Dr. Durfee

Huygen’s Construction of a Spherical Huygen’s Construction of a Spherical WaveWave

Huygen’s Construction of a Plane WaveHuygen’s Construction of a Plane Wave