Lens Converging Diverging Simulator app for iPhone and iPad

About
An open source physics at Singapore simulation based on codes written by Fu-Kwun Hwang and Loo Kang WEE.
more resources can be found here
http://iwant2study.org/ospsg/index.php/interactive-resources/physics/04-waves/04-light
Introduction
Thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces.
Rays follow simple rules when passing through a thin lens, in the paraxial ray approximation:
1. Any ray that enters parallel to the axis on one side of the lens proceeds towards the focal point F on the other side.
2. Any ray that arrives at the lens after passing through the focal point on the front side, comes out parallel to the axis on the other side.
3. Any ray that passes through the center of the lens will not change its direction
The equation is
1/u+1/v = 1/f
where
u is object distance to lens center line
v is image distance to lens center line
f is focus length of the lens

Interesting Fact
This simulation can allow for object to be on the right side of the lens, which is a lot harder to code than the typical one sided object on the left of the lens. It also comes will dotted light rays lines for virtual image and solid lines for real images. Applications of the different ranges of focus length are coded inside the simulation too.

Acknowledgement
My sincere gratitude for the tireless contributions of Francisco Esquembre, Fu-Kwun Hwang, Wolfgang Christian, Félix Jesús Garcia Clemente, Anne Cox, Andrew Duffy, Todd Timberlake and many more in the Open Source Physics community. I have designed much of the above based on their ideas and insights, and I thank the OSP community for which Singapore was honored with 2015-6 UNESCO King Hamad Bin Isa Al-Khalifa Prize for the Use of ICTs in Education.

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