Exit angle and n2?

  • Thread starter DrMcDreamy
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  • #1
DrMcDreamy
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Homework Statement



This is a two part problem:

2) As shown in the figure, a light ray is incident normally on one face of a 26◦–64◦–90◦ block of dense flint glass (a prism) that immersed in water. Find the exit angle θ4 of the light ray (Assume the index of grass is 1.69, and that of water is 1.333.) Answer in units of ◦.

attachment.php?attachmentid=32011&stc=1&d=1297117641.jpg


3) A substance is dissolved in the water to increase the index of refraction. At what value of n2 does total internal reflection cease at point P ?

Homework Equations



n1sin[tex]\theta[/tex]1=n2sin[tex]\theta[/tex]2

The Attempt at a Solution



My work:

attachment.php?attachmentid=32012&stc=1&d=1297117724.jpg


attachment.php?attachmentid=32013&stc=1&d=1297117921.jpg


I put in the answer to number 2 and it said its wrong. What I am doing wrong? Can you guys guide me through the problem? TIA!
 

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Answers and Replies

  • #2
DrMcDreamy
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Anybody?!
 
  • #3
rl.bhat
Homework Helper
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In problem 2, theta3 = 180 - (26 + 26 + 90)
 
  • #4
DrMcDreamy
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So it would be:

[tex]\theta[/tex]3=180-(26+26+90)=38[tex]\circ[/tex]

n3sin[tex]\theta[/tex]3=n4sin[tex]\theta[/tex]4
1.69sin38=1.33sin[tex]\theta[/tex]4
[tex]\frac{1.0405}{1.33}[/tex]=sin[tex]\theta[/tex]4
sin-10.7823=[tex]\theta[/tex]4
51=[tex]\theta[/tex]4

And #3 is right? TIA
 
  • #5
DrMcDreamy
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*bump*
 
  • #6
SammyS
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It looks OK.
 

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