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Homework Help: Visible light and wavelengths

  1. Jun 17, 2009 #1
    1. The problem statement, all variables and given/known data

    Ok I have two questions.
    1. Light waves of which wavelength will destructively interfere due to the thickness of the bubble film? The bubble film thickness is 165 nm, with an index of refraction of n = 1.3.
    a= 430 nm
    b= 650 nm
    c= 860 nm
    d= 285 nm

    2. You are outside in the Sun blowing bubbles. As you raise the round wand to blow bubbles, you notice an array of colors on the soap film.
    Blue = 430 nanometers
    Green = 500 nanometers
    Red = 650 nanometers
    The bubble film has an index of refraction of n = 1.3.

    a. How thick is the film where you see yellow?

    b. How thick is the film where you see cyan?

    2. Relevant equations

    1. 1/2 of a wavelength is destructive.
    2. There are many equations but i dont know which one is right for the problem I am not sure how to find the thickness.

    3. The attempt at a solution

    1. A will destructively interfere with the bubble film
    1/2x430= 215
    215/1.3= 165
    (my answer not 100% sure but im pretty sure just need confirmation)

    2. yellows wavelength is 570 nm
    cyans is 470 nm
    I am not sure what to do to find the thickness. can someone help please.

    Thank you
  2. jcsd
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