A convex lens, or converging lens, is a lens that is curved outward (convex): the ends are narrow and the middle is wide. Light passing through a convex lens is converged to a point. This point is also called a focal point. A convex lens can produce either a real or virtual image. Convex lens Taken by fir0002 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Convex lens Taken by fir0002 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... A lens. ... In mathematics, an object is convex if for any pair of points within the object, any point on the straight line segment that joins them is also within the object. ... A focal point may mean the same as focus. ...
There are three kinds of rays drawn from an object, through the lens, and after the lens used to pinpoint focus of an image: Rays entering parallel to the axis will pass through the focal point on the image side of the lens. Light passing through the point one focal length from the lens along the axis will be diffracted so that it is parallel to the axis, and light passing through the center will not be diffracted at all.
Compare:concave lens. concave lens diverging light rays A concave lens is a lens with inward-curving (concave) surfaces: the ends are wide, the middle is thin. ...
If the lens is biconvex or plano-convex, a collimated or parallel beam of light travelling parallel to the lens axis and passing through the lens will be converged (or focused) to a spot on the axis, at a certain distance behind the lens (known as the focal length).
The beam after passing through the lens appears to be emanating from a particular point on the axis in front of the lens; the distance from this point to the lens is also known as the focal length, although it is negative with respect to the focal length of a converging lens.
where n is the refractive index of the lens material, n' is the refractive index of the medium which the lens is in and d is the distance along the lens axis between the two surfaces (known as the thickness of the lens).
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