nwater·sin(?) = nair·sin(90) c v Snell's Law n1·sin(σ1) = n2·sin(σ2) nwater·sin(?) = nair·sin(90) Air – “fast” Water – “slow” ? Critical Angle

Total internal reflection. n1sin1= n2sin2 If θ2=90 sin2=1  θ1= θc  n1sinc= n2 Critical Angle

ndiamond·sin(σ1) = nair·sin(σ2) c v Snell's Law ndiamond·sin(σ1) = nair·sin(σ2) ·sin(?) = ·sin(90) 299,792,458 123, 932,393 299,792,458 299, 702,547 ? = 24.4° http://www.diamondocean.com/news/images/20071015_114_1.jpg $15 Million 84 Carat Diamond Up For Auction! 24.4°

Light Box activity

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LAB – Index of Refraction Find the speed of light of in this. What angle of incidence would produce the critical angle on the opposite face of the equilateral tiangle? Then test! ? θc nacrylic = 1.5 θc = 41.8° ?= 27.9°

Total Internal Reflection Web Link: Total internal reflection Examples: Fiber Optics Diamonds Total internal reflection

Air – “fast” Water – “slow” http://ibis.tau.ac.il/twiki/pub/Zoology/Lotem/Mylab/Scuba_Diver_5.jpg http://www.cypyp.com/images/Customer%20Images/Ankara/Late%202008/airplane_clipart_pilot.gif

Atlee High School, Student: Matthew Jay Rohr, Teacher: Jeremy Watts

http://www. lightandmatter http://www.lightandmatter.com/html_books/3vw/ch04/figs/fish-reflection.jpg

The glass fibre has a second glass cladding of a lower n (and then a plastic covering) This allows the light to totally internally reflect down the fibre.

Optical fiber communication system Electrical/optical converter Decoder Electric signal Fiber Optical/electrical converter Encoder Repeater Digital encoding scheme for optical communications “One” “Zero” High-power pulse  “one” Low-power pulse  “zero” High-power pulse  “One”

Medicine a) to view An endoscope can be inserted into the body with minimal surgery (non-invasive).

Once in the body it can diagnose and/or treat a condition.

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