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Help with Physics

  1. Haunty profile image85
    Hauntyposted 6 years ago

    This is a homework assignment for my colleague's daughter at the uni. We can't solve it. Can someone help?

    The big triangle is a prism.


    http://s3.hubimg.com/u/4384018_f248.jpg

    Link has bigger image.
    http://img52.imageshack.us/img52/1740/prismk.jpg

    1. profile image62
      Slushyposted 6 years ago in reply to this

      The 90° angle in the middle of the prisma, between X und Z does not look at all like 90°... is it just a rough drawing or are maybe some of the data wrong?

      EDIT: I just realised... is this supposed to be a 3D drawing? Then the "weird" 90 degree angle would make sense smile

    2. RDSPhD profile image62
      RDSPhDposted 6 years ago in reply to this

      Just watch this 14min video about snell's law, that's all you need to know wink

      http://www.khanacademy.org/video/refrac … st=Physics

      In your case n=1.58, now you should be able to solve it wink

      greetz RDSPhD

      1. vydyulashashi profile image60
        vydyulashashiposted 6 years ago in reply to this

        I guess this is 3D drawing coz according to physics opposite anglesshould be same. So according to the prism Y should be equal to Z  and hence siny/sinz should be equal to one. But it it is not ,according to the data you gave.
        I guess this needs some higher physics analyst

        1. RDSPhD profile image62
          RDSPhDposted 6 years ago in reply to this

          I think it's just a sketch and not detailed, I have dealt with thousands of incorrect sketches even on the highest level of my physics studies wink Sometimes Profs or their assistants are just too lazy to not only put some new numbers there every year but also to redraw the sketches wink

          Oh and siny/sinz doesn't need to be 1 necessarily! Only when light travels in vacuum! If the prism is denser (which it is of course) n>0 ! n=1.58 suggests that the prism might be made out of Polycarbonate wink

    3. vydyulashashi profile image60
      vydyulashashiposted 6 years ago in reply to this

      Since opposite angles must be same Y must be equal to 45+z(look carefully on that deviated angle)
      Now I guess in that internal triangle,which you mentioned 90 degrees and if it is correct, the other angles must be 45 and 45 and that implies x must be 45.
      I guess am not correct 100% but have a look on this solution!

      1. ediggity profile image61
        ediggityposted 6 years ago in reply to this

        The internal triangle is a 30 60 90 triangle with sides of 1,sqrt 3, 2.  Use X to work backwards to find out the interior and exterior angles, then use Snell's law to solve for Y.

  2. ediggity profile image61
    ediggityposted 6 years ago

    Just glancing, it looks like an equilateral triangle, making X = 60 deg.  Now that you know X you can use Snell's law:

    ni*sin(i)=nI*sin(I) to solve for y.

    Just make sure not to confuse the ray bending toward the normal.  Additionally, I assume air is ni=1.

  3. profile image0
    zampanoposted 6 years ago

    It's just an optics exercice.
    Refraction is the subject.

  4. paradigmsearch profile image89
    paradigmsearchposted 6 years ago

    All I remember from that bygone era is Chief soh cah toa. smile

 
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