# Copie de 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)

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