Thin convex lens:
O: The boject
I: The image
C: The optical center
F: The principal focus
F': The principal focus in front of the mirror
How to use:
Adjust the point O to move the object.
Adjust the height of the object by the slider.
If the object is located uF in front of the mirror,
if u/(u-1) > 0, the image is located [u/(u-1)]F behind the mirror,
if u/(u-1) < 0, the image is located -[u/(u-1)]F in front of the mirror.
