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Homework Help: Fish in a Fish bowl?

  1. Apr 3, 2008 #1


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    Q. There is a fish in a spherical fish bowl of radius r filled with water. The fish is at a distance l from the surface of the tank. An observer in air views the fish at a distance d from the tank.

    Please see the attachment for the image.

    I am supposed to find the optical power and focus length of the water-air interface, the magnification power of the fish tank and an expression for the distance (L) between the obsever and optical image of the fish.

    Here are the attempts I have made:

    Optical power = (n1-n2)/(-r)

    Focus Length = f'=n2/P = -n2r/(n1-n2)
    I used f' because I think it is a virtual image?

    Magnification Power = -(Image Distance/Object Distance) =-((L-d)/-r)

    L=(-n1/r + n2/l)

    Can anyone tell me if these are correct or if I am at least going along in the right direction?

    Attached Files:

    Last edited: Apr 4, 2008
  2. jcsd
  3. Apr 26, 2010 #2
    Try the refraction at a single surface formula

    here, n1=1.33 (water); N2=1 (air)
    and note the sign of s should be negative as the fish is not on the incident-light side of the surface.
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