REFRACTION AND REFLECTION POLARIZATION OF LIGHT

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REFRACTION AND REFLECTIONPOLARIZATION OF LIGHT

• Emily Kozlowski and April Mante

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DEFINITION OF REFRACTION

• Refraction is the change in direction of a wave
  due to a change in its speed. This is most
  commonly observed when a wave passes from one
  medium to another at an angle.

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http//www.stmary.ws/highschool/physics/home/notes
/waves/refraction/fishRefraction.html
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Is It really bending????????

• Straight or bent?  What happens when you look at
  the pencil through the side of the glass?  Light
  play tricks on your eyes.  The pencil looks
  bent.  This is because light travels slower
  through water than through air.  As the light
  enters the glass of water it slows down(changes
  direction) and as it leaves the glass it speeds
  up again therefore making the pencil look as
  though it is bent

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Refraction
     

• A lens is a piece of transparent material.  It
  is usually made of glass and has at least one
  curved surface.
• The curved surface/surfaces of a lens bends the
  light.

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The angle of incidence is measured from the
normal to the incident ray. The angle of
refraction is measured from the normal to the
refracted ray.
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• If light enters a more optically dense material,
  the speed decreases and the light bends towards
  the normal.
• If light enters a less optically dense material,
  the speed increases and the light bends away from
  the normal.

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• The angle of incidence that results in an angle
  of refraction of 90 degrees is call the critical
  angle.
• If the angle of incidence is greater than the
  critical angle total internal reflection occurs.

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Did you know.... A sunset is an optical illusion
        Refraction allows youto see the
sun even after it has set. 
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Reflection
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• Reflection is the change in direction of a wave
  front at an interface between two different media
  so that the wave front returns into the medium
  from which it originated from.
• A flat mirror called a plane mirror is a good
  reflector of light. A normal is formed when a ray
  of light strikes the mirror at a right angle.

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Reflection

• Reflection- the return of light, heat, sound,
  etc., after striking a surface.
• bouncing of light off a mirror or mirror-like
  surface.

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• -Reflection may even occur on water and clouds
• Mainly, there are two types of reflection,
  specular and diffused.
• Light being reflected of a smooth surface is
  Specular. When light strikes this smooth surface,
  all the reflected rays are in line with each
  other. An image is formed.
• If the surface is rough, the light scatters

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  b. Diffuse Reflection reflection off an
irregular surface causing light to scatter (no
image)
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Regular Reflection reflection off a polished
surface (produces images)
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Polarization of Light

• Polarizing filters are used in photography and in
  certain kinds of sunglasses.
• But polarization is also used in digital watches
  and laptop screens.

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QUIZ
1. ________ is the change in direction of a wave
due to a change in its speed
2. The ___________ is measured from the normal to
the refracted ray.
3._____________- reflection off an irregular
surface causing light to scatter
4._________ reflection off a polished surface
5. If light enters a less optically dense
material, the speed ______ and the light bends
____ from the normal
6. The angle of incidence that results in an
angle of refraction of 90 degrees is call
the__________.
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ANSWERS

1. Refraction
2. Angle of refraction
3. Diffuse reflection
4. Regular reflection
5. Increases , away
6. Critical angle

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http//www.stmary.ws/highschool/physics/home/anima
tions3/default.htm
http//www.physicsclassroom.com/Class/
http//www.flickr.com/photos/isabelfotografie/page
7/
http//www.bing.com/images/search?qangleofincid
enceFORMBIFDfocal698642f006cbe01c3d956f4712d07
689furlhttp3A2F2Fsciencecity.oupchina.com.hk
2Fnpaw2Fstudent2Fglossary2Fimg2Fangle_of_incid
ence.jpg
http//en.wikipedia.org/wiki/Reflection
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Refraction /reflection/polarization of light

• By Nick Valentin And Keaon Naghizadeh

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What is light?

• Light is an electromagnetic radiation that can
  produce a visual sensation, which is used in many
  ways like refraction, reflection and polarization
  of it.

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What is Refraction ?

• Occurs when light passes into a new material and
  starts to move at a different speed. If the ray
  hits the surface of the material at an angle, the
  ray will be bent.
• Example is when you stick a pencil into a glass
  of water the rays form the light in the room hits
  the surface of the pencil at a different angle
  and different speed which cause the pencil to
  look distorted .

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Examples of Refractions
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Snells law of refraction

• The bending of light called refraction was first
  studied by Rene Descartes and Willebrord Snell,
  around the time of Kepler and Galileo.
• To understand their result you have to define to
  angles, The angle of incidence is the angle at
  which the light ray strikes the surface . It is
  measure from the normal to the surface. The
  second angle, is the angle of refraction . This
  is the angle in which the transmitted light
  leaves the surface.

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Continue Snells Law

• In 1621 Snell found that when light went from air
  into a transparent substance , the sines of the
  angles were related by the equation .
• N1Sin?1n 2 Sin?1 .
• In this equation N is a constant that depends
  on the substance , not on the angles called the
  index of refraction.
• ?1 is the angle at which the light rays strikes
  the surface , which is measure from the normal to
  the surface
• ?2 is the angle at which the transmitted light
  that leaves the surface.

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Reflection

• Reflected waves are simply those waves that are
  neither transmitted or absorbed, but are
  reflected from the surface of the medium they
  encounter.
• Reflection does not just happen with a mirror, it
  happens with any flat surface that doesnt
  transmitted or absorbed.

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Law of Reflection

• It states that when an object bounces off a flat
  surface, the angle it at which it hits the
  surface will be equal to the angle at which it
  bounces away.
• law of reflection can also be stated as that
  the angle of incidence is equal to the angle of
  reflection
• No matter what the incidence and refection angle
  must be equal.

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Examples of the law of reflection

• IF you hit a pool ball against a bumper of a
  pool table, the initial angle use to hit the ball
  against the wall is the incidence angle.
• As the ball hits the bumper it rebounds at an
  angle that is equal to the incidence .This new
  angle is called reflection.

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Polarization of light

• The process of transforming unpolarized light
  into polarized light is known as Polarization.
• There are to specific types of polarization
  called polarization by filtration and
  polarization by reflection
• To full understand the concept of this look at
  this figure

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Polarization of Filtration

• Polarization can be understood by considering a
  rope model of light waves. The transverse
  mechanical waves in the rope represent transverse
  light waves. The slots represent what is referred
  to as the polarizing axis of the polarizing
  medium.

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Quiz!!!!!

• 1. Angle of incidence  a)optical
  density  b)angle of reflection  c)index of
  refraction
• 2. One of the laws of reflection of light states
  The angle of _______ is always equal to the
  angle of reflection.
• a)convergence
• b)  incidence
• c)  refraction

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More quiz

• 3.What is "refraction"?
• a)When light goes into space
• b)When light bounces off another object
• c)When light bends at a boundary
• d)When light passes through water and continues
  in straight line

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Even more

• 4.What does "Snell's Law" state?
• a)A ray of light bends in such a way that the
  ratio of the sine of the angle of incidence to
  the since of the angle of refraction is a
  constant
• b)That light does not come from the sun
• c)That light does come from the sun
• d)That everyone is unique

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Believe it or notmoree

• 5.What is the ray, which first strikes a surface,
  called?
• a)Primary ray
• b)Primary color
• c)Reflection ray
• d)Incident ray

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Answer Key

• 1.B
• 2.B
• 3.C
• 4.A
• 5.D

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Bibliography

• hyperphysics.phyastr.gsu.edu/Hbase/geoopt/refr.htm
  l
• http//id.mind.net/zona/mstm/physics/light/rayOpt
  ics/reflection/reflection1.html
• http//www.worsleyschool.net/science/files/reflect
  ionlaw/page.html
• http//en.wikipedia.org/wiki/Snell's_law
• Physics Principles and Problem Text book