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Homework Help: Optics problems

  1. Jan 4, 2008 #1
    Problem 1:
    A thin hollow glass sphere has a radius of 1 m. A coin is placed at the bottom of the glass sphere. 2.09 metre cube of a liquid of refractive index 1.5 is poured into the glass shpere. A person is viewing the object vertically. What is the apparent depth of the coin?

    Im not sure if there will be refraction at the glass surface and i dont know how to consider it. I need help.

    Problem 2:
    A convex lens has a thickness 0.2m. The radii of curvature of the two surfaces are 1 and 2 m respectively. An object is kept at a distance of 10m from the left surface. The right surface is silvered. Find the position of final image.

    I considered refraction at surface 1 , refration at surface 2, then reflection and then again refraction at surface 2 and refration at surface 1.
    Is that right?
  2. jcsd
  3. Jan 4, 2008 #2


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    1, The glass is a 'thin shell' so ignore it's refraction. You just have to consider a plano-spherical lens of water of whatever thickness that depth works out as.

    2, Nearly, there is no refraction at surface 2 because there is no other medium between the glass and the silver. ( Ignoring complicated stuff about evervescent waves and surface plasmons).
  4. Jan 5, 2008 #3
    My book says, when there is a silvered lens, we are supposed to consider it as a lens and a mirror seperately and consider 4 refractions and 1 reflection. I am unable to verify this from any standard textbook. Any source you'll suggest?
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