I need solution for this problem:
A double convex lens has a diameter of 5 cm and zero thickness at its
edges. A point object on an axis through the center of the lens
produces a real image on the opposite side. Both object and image
distances are 30 cm, measured from a plane bisecting the lens. The
lens has a refractive index of 1.52. Using the equivalence of optical
paths through the center and edge of the lens, determine the thickness
of the lens at its center.

This problem from book "Introduction to Optics" second edition by
Pedrotti. problem # 3-3.

Howdy al3in-ga,

To view the original of the following document, you will need a PostScript
viewer.  I use Ghostgum's GSview, which you can download at no cost at the
Ghostgum web site.
http://www.ghostgum.com.au/

"GSview is a graphical interface for Ghostscript, an interpreter for the
PostScript language and Portable Document Format."

The solution to your problem can be found on this University of Michigan
PostScript page.  Here is a transcription of that page, but I suggest you
look at the original for the proper (graphical) notation.
http://www-mhp.physics.lsa.umich.edu/~roe/p402exsep16.ps

"The path length for light going from the object to the edge of the lens
and then to the image is ...

2 x [the square root of [(2.5)^2 + 30^2]] = 60.21 cm.

The optical path length for light going directly through the lens is ...

2 x 30 + (n-1) x thickness

Equating these two expressions, we find ...

Thickness = 0.21 / [1.52 - 1] = 0.40 cm."

If you need any clarification, feel free to ask.


Search strategy:

Google search on: "double convex lens has a diameter"
://www.google.com/search?q=%22double+convex+lens+has+a+diameter%22

Looking Forward, denco-ga - Google Answers Researcher

Perfect, Thank you alot.

My pleasure al3in-ga, and thanks for the 5 star rating.

Looking Forward, denco-ga - Google Answers Researcher