Prisms, total internal reflection, polarization, how we see color, how vision is corrected and rainbows.

Prisms

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.

              

   

Fiber Optics

Optical FibersOptical 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.

29.12 Total Internal Reflection

Total Internal Reflection

Total Internal Reflection

http://www.phy.ntnu.edu.tw/java/optics/path_e.html

http://micro.magnet.fsu.edu/primer/java/refraction/criticalangle/index.html

Polarization of Light

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/polarizers/Polarizer.htm

When sunlight passes through a prism, it separates into a spectrum of all the colors of the rainbow.

28.1 The Color Spectrum

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.

Isaac Newton—discovered that white light is composed of seven (or six) different colors of light

White Light

Red

Orange

Yellow

Green

Blue

Violet

A prism disperses white light into its primary frequencies of color

Dispersion of white light into component colors

http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html

R Nave

Prisms

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/rainbow.html

http://micro.magnet.fsu.edu/primer/java/refraction/refractionangles/index.html

Refraction

http://freespace.virgin.net/gareth.james/virtual/Optics/Refraction/refraction.html

http://www.physicsclassroom.com/Class/refrn/u14l1f.html

http://acept.la.asu.edu/PiN/mod/light/opticsnature/pattLight4Obj1.html

http://www.wrh.noaa.gov/Flagstaff/science/skyblue.htm

http://www.cordonline.net/laserapplets/

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.

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.)