Transcript what is light? - Fort Thomas Independent Schools

Prisms, total internal
reflection, polarization, how
we see color, how vision is
corrected and rainbows.
Prisms
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High frequency light in a transparent medium travels
slower than low frequency light (red light travels
faster than violet light)
Thus, the different colors are refracted at different
angles.
When white light is refracted twice, and the second
surface is not parallel to the first, the dispersion is
noticeable, thus the colors are observed.
If the two boundaries of the medium are parallel, the
refractive effects at the first boundary are reversed at
the second boundary.
Total Internal Reflection
Light can be reflected off a transparent
medium boundary at a certain angle.
 This angle is called the critical angle.
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Fiber Optics
29.12 Total Internal Reflection
Optical Fibers
Optical fibers, sometimes called light pipes, are transparent fibers that pipe light
from one place to another.
They do this by a series of total internal reflections.
Optical fibers are useful for getting light to inaccessible places.
Mechanics and machinists use them to look at the interiors of engines, and
physicians use them to look inside a patient’s body.
Total Internal Reflection
Total Internal Reflection
http://www.phy.ntnu.edu.tw/java/optics/p
ath_e.html
 http://micro.magnet.fsu.edu/primer/java/
refraction/criticalangle/index.html
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Polarization of Light
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Light consists of waves vibrating in all planes
(360o).
A polarizer allows only the light wave along
one plane to pass through.
Two polarizers if oriented at right angles will
cancel all light.
Glare (reflected light polarized in a plane
parallel to a non-metallic surface) is greatly
reduced when using polarized lenses.
http://lectureonline.cl.msu.edu/~mmp/kap24/p
olarizers/Polarizer.htm
28.1 The Color Spectrum
When sunlight passes through a prism, it separates into a
spectrum of all the colors of the rainbow.
roygbiv
dispersion
The phenomenon of incoming light of
different wavelengths being bent at
different angles when passing through a
medium.
 Red light is bent the least; violet the
most
 Prismatic effect (Dark Side of the Moon)
produces rainbow colors: White light is
separated into roygbv.
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Isaac Newton—discovered that white light is
composed of seven (or six) different colors of
light
Dispersion of white light into component colors
Red
Orange
White
Light
Yellow
Green
Blue
Violet
A prism disperses white light into its
primary frequencies of color
http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html
R Nave
Prisms
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http://www.physics.mun.ca/~jjerrett/dispersion
/prism.html
 http://micro.magnet.fsu.edu/primer/java/prism/
index.html
Rainbows, etc.
http://mysite.verizon.net/vzeoacw1/rainb
ow.html
 http://micro.magnet.fsu.edu/primer/java/
refraction/refractionangles/index.html
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Refraction
http://freespace.virgin.net/gareth.james/
virtual/Optics/Refraction/refraction.html
http://www.physicsclassroom.com/Class/r
efrn/u14l1f.html
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http://acept.la.asu.edu/PiN/mod/light/opt
icsnature/pattLight4Obj1.html
 http://www.wrh.noaa.gov/Flagstaff/scien
ce/skyblue.htm
 http://www.cordonline.net/laserapplets/
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polarization
Light that is reflected or transmitted
through specific materials such that all
vibrations are oriented on single plane.
 A polarizer allows only one plane of light
through.
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polarization
1st polarizer eliminates
all but one plane
2nd polarizer when
oriented at a right
angle to this plane
eliminates the
remaining plane
polarization
Sunlight is horizontally polarized when
reflecting off a surface, producing glare
(off a pond, river, car, road, etc.)