A wonderful lens-a glass of water(highschool physics)

[jadelamlam]

a wonderful lens--a glass of water(high school physics)

Homework Statement

http://i615.photobucket.com/albums/tt234/chandaiman199111/untitled.jpg

Homework Equations

The Attempt at a Solution

Well,I have already thought for 5 hours,but I couldn't get what it means.
My senior form or even a-level textbook haven't mentioned any information about spherical convex lens and cylindrical convex lens,so I have tried to draw ray diagram by myself to understand it.Unfortunately,I have attempted for many times but I couldn't draw anything accurately.

I have searched in wiki and other websites.However,I couldn't find the thing I need.

Can anyone help me to draw ray diagrams,or provided some websites for me?

Please forgive for my foolishness :(

Really thanks very much :)

 

[Simon Bridge]

Draw a picture of the cross-section of a glass of water - it will be two concentric circles.
Between the outer two circles is the glass - what is the refractive index of glass (in general)? Inside the middle circle is all water - what is the refractive index of water? More or less than glass?

Do you know how to use Snell's law to draw a ray as it refracts through an object?

Draw two parallel rays approaching the glass and use your understanding of Snell's Law to sketch what happens to the rays as they pass through.

The place where the two rays cross has a special name - what is it?

From there you can draw a standard ray-diagram with three principle rays and everything.