Copy of Convex lens: lensmaker's equation
The Lensmaker's equation describes the relationship between lens material (index n), radii of curvature of spherical lens surfaces, and locations of object (light source) and image.
This applet allows you to explore the conditions under which the Lensmaker's equation is true -- or nearly true -- and the conditions that violate the Lensmaker's equation.
To send parallel rays through the lens, use the Input bar to put the source at a large negative x distance: For example,
Source=(-1E10,0)