Ray diagram for double convex and double concave lenses.[br][br]Drag the point f or f' (which ever is light blue) to change the focal length of the lens. [br]Drag the point E (light blue) to change the location (horizontal drag) and height (vertical drag) of the object.[br][br]The thickness of the lens does not correspond to the focal length.

What phenomenon does the failure of all 3 lines to cross neatly at a single point demonstrate?[br]When is the image right side up?[br]When is the image real?[br]When is the image larger than the object?[br]What happens when you drag f through the lens to the other side? How is that related to the sign conventions for lenses?