REFRACTION AND REFLECTIONPOLARIZATION OF LIGHTEmily Kozlowski and April Mante

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.

http://www.stmary.ws/highschool/physics/home/notes/waves/refraction/fishRefraction.html

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

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.

     

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.

•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.

•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.

Did you know....A sunset is an optical illusion

   

 Refraction allows you

to see the sun even after it has set. 

Reflection

•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.

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

Reflection

• -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

 

b. Diffuse Reflection – reflection off an irregular surface causing light to scatter (no image)

Regular Reflection – reflection off a polished

surface (produces images)

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.

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__________.

QUIZ:

1.Refraction2.Angle of refraction3.Diffuse reflection4.Regular reflection5.Increases , away6.Critical angle

ANSWERS

http://www.stmary.ws/highschool/physics/home/animations3/default.htm

http://www.physicsclassroom.com/Class/

http://www.flickr.com/photos/isabelfotografie/page7/

http://www.bing.com/images/search?q=angle+of+incidence&FORM=BIFD#focal=698642f006cbe01c3d956f4712d07689&furl=http%3A%2F%2Fsciencecity.oupchina.com.hk%2Fnpaw%2Fstudent%2Fglossary%2Fimg%2Fangle_of_incidence.jpg

http://en.wikipedia.org/wiki/Reflection

Refraction /reflection/polarization of light

By Nick Valentin And Keaon Naghizadeh

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.

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 .

Examples of Refractions

Snell’s 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.

Continue Snell’s 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 .

• N1Sinθ1=n 2 Sinθ1 . • In this equation “N” is a constant that depends on

the substance , not on the angles called the index of refraction.

• θ1 is the angle at which the light rays strikes the surface , which is measure from the normal to the surface

• θ2 is the angle at which the transmitted light that leaves the surface.

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 doesn’t transmitted or absorbed.

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.

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.

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

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.

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)convergenceb)  incidencec)  refraction

•

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

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

Believe it or not…moree

5.What is the ray, which first strikes a surface, called?

a)Primary ray b)Primary color c)Reflection ray d)Incident ray

Answer Key

•1.B•2.B•3.C•4.A•5.D

Bibliography

•hyperphysics.phyastr.gsu.edu/Hbase/geoopt/refr.html

•http://id.mind.net/~zona/mstm/physics/light/rayOptics/reflection/reflection1.html

•http://www.worsleyschool.net/science/files/reflectionlaw/page.html

•http://en.wikipedia.org/wiki/Snell's_law•Physics Principles and Problem Text book