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Homework Help: Resolving Distant Objects question

  1. Jun 4, 2008 #1
    [SOLVED] Resolving Distant Objects question

    Consider a telescope with a small circular aperture of diameter 2.0 centimeters.

    If two point sources of light are being imaged by this telescope, what is the maximum wavelength (lambda) at which the two can be resolved if their angular separation is 3.0 x 10^-5 radians?

    Relevant equation - sin(theta) = 1.22 x lambda/D

    I get - Dsin(theta)/1.22 = lambda
    0.02 x sin(3.0 x 10^-5)/1.22 = lambda
    = 4.92 x 10^-7
    therefore lambda = 0.492 nm

    It doesn't seem correct. Any help would be very appreciated.
  2. jcsd
  3. Jun 4, 2008 #2


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    You're correct its just you have the units confused. It will be 492nm not 0.492. Remember a nanometer is 1 billionth of a meter. So one nanometer is 1x10-9 m.
  4. Jun 4, 2008 #3
    yeah i just figured it out and was coming back to post as you replied, thanks anyway though.
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