Reflection and Refraction .ppt

8/9/2019 Reflection and Refraction .ppt

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Reflection and Refraction

Physics

Mrs. Coyle


2/27

Reflection

When a wave reaches a boundary it is:

Partially reflected (bounces off surface)Partially transmitted through surface.


3/27

aw of Reflection

!ngle of incidence " !ngle of reflection


4/27

#ote

$ %he angle of incidence is formedbetween the incident ray and thenormal.

$ %he angle of reflection is formedbetween the reflected ray and thenormal.


5/27


6/27

iffuse Reflection

$ Reflection from a rough surface.


7/27

https://reader010.{domain}/reader010/html5/0604/5b149b8f6b2bc/5b149b951ae19.jpg
http://micro.magnet.fsu.edu/primer/java/reflection/specular/specularjavafigure1.jpghttp://micro.magnet.fsu.edu/primer/java/reflection/specular/specularjavafigure1.jpg


8/27

Reflection from a Plane Mirror

di=do

hi=ho


9/27

%y'e of mage

$ Real or *irtual

$ +nlarged or Reduced

$ +rect or nverted


10/27

What is the minimum mirrorheight re,uired for a 'ersonto see their full self in the

mirror-


11/27

int: Com'are !/ to C

A

D

B

C


12/27

Refraction

$ When a wave crosses a boundarybetween Medium 0 and Medium 12 thewave changes direction because itchanges velocity.

$ 3re,uency remains constant.

$ *elocity changes as a result ofwavelength change.

$ &imulations

$ htt':44www.walter5fendt.de4'h06e4refraction.htm 7777777

$ htt':44www8.interscience.wiley.com:904legacy4college4halliday46;081.htm


13/27

Refraction


14/27

+>am'le

Less Rigid

Medium

More RigidMedium

Refracted

ray bendstowards

thenormal.

Incident

Ray

Refracted Ray


15/27

nde> of Refraction2 n

n = c / v

$ c :the s'eed of light in a vacuum28 > 09 m4sec

$ v : s'eed of light in the medium.

$ n: medium?s inde> of refraction

$ n>1 (hy!"


16/27

Indices of Refraction

*acuum 0.

!ir 0.8

Water 0.88+thanol 0.8=

Crown glass 0.


17/27

#ote

$ %he s'eed of light has a lower s'eedin a more o'tically dense medium.


18/27

Problem

$ What is the s'eed of light in ,uartA-

$ !nswer: 0.B; > 0 9 m4s


19/27

&nells aw

$ n1 sin 1 = n# sin


20/27

#ote

When the incident ray travels from

a less o$tically dense medium(low n"

to

a more o$tically dense medium

(higher n"

then the refracted ray bends

towards the normal.


21/27

Problem

$ What is the angle of refraction whena ray from air with an angle ofincidence of 1< o is incident to water-

$ raw the ray diagram.

$ !nswer: 09.


22/27

%otal nternal Reflection

$ Can occur when ray goes fromhighern to lowern.

$ !bove a Critical angle (of incidence)the ray is reflected2 not refracted

$ htt$://www.walter%fendt.de/$h1&e/refraction.htm

$ 3or 'roblems2 set the angle ofrefraction to B2 and solve for criticalangle


23/27

Problem

$ 3ind the critical angle for a light raythat is incident from water to air.

$ !nswer: 69.9 o


24/27

is'ersion$ %he inde> of refraction of glass is different

for the colors that maDe u' white lightbecause the s'eed of light is slightlydifferent in glass for each fre,uency oflight. (n vacuum all colors have s'eedc"8>09m4s.)


25/27

Problem

%he inde> of refraction for crownglass for red light is 0.


26/27

Mirage

http://www.warren-

wilson.edu/~physics/PhysPhotOfWeek/!!"PPOW/!!"!#1$oad%irage/&%'(

1)))%irage*rop+!!.jpg


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Mirage%otal internal reflection occurs because

hot air has a lower n2 than cold air.

http://www.warren-wilson edu/~physics/PhysPhotOfWeek/!!"PPOW/!!"!#1$oad%irage/inde, html

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Reflection and Refraction .ppt