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Critical angle

  1. Jun 5, 2015 #1
    Greetings,
    Do we use Absloute refractive index when finding crtical angle ?

    if it was two mediums ( not vacuum or air) how would i calculate the critical angle ? I mean i get confused when I find relative refractive index because sometimes i get sine inverse greater than 1 which give no solution .

    Thank you in advance.
     
  2. jcsd
  3. Jun 5, 2015 #2

    blue_leaf77

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    Snell's law reads as ##n_1 \sin{\theta_1} = n_2 \sin{\theta_2} ##. Now if we assume ##n_1## to be greater than ##n_2## and ##\theta_2 = 90^0##, what will you end up with?
    What can you then conclude for the requirement for ##n_1## and ##n_2## so that total internal reflection which is associated with critical angle can take place?
     
  4. Jun 5, 2015 #3
    it will end up with ##n_1 \sin{\theta_1} = n_2 ? , n1 is denser than n2 since its greater than
    I know the fact that critical angle occurs only from denser medium to less dense , and that's why I get confused when I find relative refractive index
     
  5. Jun 5, 2015 #4

    blue_leaf77

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    If you had known this, then why would you get sine inverse greater than one when calculating a critical angle?
     
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