Thin lenses. Arrows indicate direction of travel of light. Virtual rays are drawn as dashed lines.

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Drag E to move and resize the object. Drag f to change the focal length.

What happens when the object crosses the focal point?

What happens when the focal point crosses the lens?

What happens when the object gets tall compared to the lens?

When can you get a real image?

Lenore Horner, Created with GeoGebra