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Finding angle of refraction given angle of incidence?

  1. Apr 26, 2016 #1
    Can someone help me in solving this question ?

    my attemp is sin42/sin 90 to get the refractive index then n =sin i/sin r to get c
    and for b n=1/sinc
    Physics.jpg
     
  2. jcsd
  3. Apr 26, 2016 #2

    TSny

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    Welcome to PF!

    Try to answer part (i) first by examining the diagram and using a little geometry.
     
  4. Apr 26, 2016 #3
    Thanks for responding but i am trying but cant figure it out its probably right there in my face but i just cant see it yet
     
  5. Apr 26, 2016 #4

    TSny

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    What is the value of the angle DBM shown below?
     

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  6. Apr 26, 2016 #5
    that would be 90 ?
     
  7. Apr 26, 2016 #6

    TSny

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    Yes, I think that's what you are supposed to assume. The fisherman's net (at D) is assumed to be essentially at the surface of the water.
     
  8. Apr 26, 2016 #7
    so there fore the angle of incidence is 90 so that means C would be a critical angle
     
  9. Apr 26, 2016 #8

    TSny

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    Yes. From the diagram, can you determine the value of the critical angle in degrees?
     
  10. Apr 26, 2016 #9
    42 ? i doubt you can just determine it from looking at the diagram as the question asks to calculate it
     
  11. Apr 26, 2016 #10

    TSny

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    Note that the line connecting point A to Nemo's eye is a straight line.
     

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  12. Apr 26, 2016 #11
    therefore c must be 180-(42+90)
     
  13. Apr 26, 2016 #12

    TSny

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    Yes
     
  14. Apr 26, 2016 #13
    well it makes sense because the answer is 48 and 48 is the critical angle of air-water boundary so now i find the refractive index 1/48
     
  15. Apr 26, 2016 #14

    TSny

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    Why 1/48?
     
  16. Apr 26, 2016 #15
    because there is a formular which says that N(Refractive index) = 1/ sin C(48) oh i see yeah im suppose to sin the 48
     
  17. Apr 26, 2016 #16

    TSny

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    Yes, good.
     
  18. Apr 26, 2016 #17
    thank you very much
     
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