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Reflection and Refraction

Reflection and Refraction

Source:  disney.fandom.com   Source:  h3ps://en.wikipedia.org/wiki/ The_Dark_Side_of_the_Moon  

Reflection and Refraction

Things  to  think  about:     •  Angles  of  incident,   reflected,  and  refracted   rays  

•  The  mediums  the  light  is   traveling  through  

•  Intensity  of  incident,   reflected,  and  refracted   rays    

•  Wavelength  of  rays    

Law of Reflection

1 1θ θʹ′ =

Snell’s Law

“The  experimental  discovery  of  this  relaHonship  is   usually  credited  to  Willebrord  Snell  (1591–1626)  and   it  is  therefore  known  as  Snell’s  law  of  refracHon.   (There  is  some  evidence  that  the  law  was  developed   centuries  earlier  in  the  Middle  East.)”  

1 1 2 2sin sinθ θ=n n

Snell’s Law

1 1 2 2sin sinθ θ=n n

Let’s  solve  for  ​𝜃↓2      ​𝜃↓2 =   ​​sin↑−1  ⁠(​​𝑛↓1 /​𝑛↓2  ​sin ⁠​𝜃↓1  )      What  happens  when  ​𝑛↓1 > ​𝑛↓2   ?          

The Speed of Light

•  The  speed  of  light  is  constant  in  a  vacuum   •  But  what  about  in  a  medium?    

𝑣=   ​𝑐/𝑛   

Source:  h3ps://www.nasa.gov/mission_pages/hubble/science/xdf.html  

eXtreme  Deep  Field  (XFD):  Light  from  these  galaxies   travels  through  the  vacuum  of  space  at  a  constant   speed  to  give  us  an  image  of  what  the  Universe  was   like  a  loooong  Hme  ago  

Wavelength and Frequency

λ λ

= n

n nλ λ<

Remember:  𝑣=𝜆𝑓  

Goals of this lab

• Find  angles,  intensiHes,  and  speeds  of  reflected  and  refracted  light   rays  

• Explore  wavelength  dependence     • Find  criHcal  angle  for  when  ​𝑛↓1 > ​𝑛↓2