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  2. Curved mirror - Wikipedia

    en.wikipedia.org/wiki/Curved_mirror

    A concave mirror, or converging mirror, has a reflecting surface that is recessed inward (away from the incident light). Concave mirrors reflect light inward to one focal point. They are used to focus light. Unlike convex mirrors, concave mirrors show different image types depending on the distance between the object and the mirror.

  3. Real image - Wikipedia

    en.wikipedia.org/wiki/Real_image

    A real image occurs at points where rays actually converge, whereas a virtual image occurs at points that rays appear to be diverging from. Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted. As the object ...

  4. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    The rear focal length f ′ is the distance from the rear principal plane H ′ to the rear focal point F ′. Front focal distance (FFD) The front focal distance (FFD) (s F) is the distance from the front focal point of the system (F) to the vertex of the first optical surface (S 1). [1] [3] Some authors refer to this as "front focal length".

  5. Virtual image - Wikipedia

    en.wikipedia.org/wiki/Virtual_image

    The image in a plane mirror is not magnified (that is, the image is the same size as the object) and appears to be as far behind the mirror as the object is in front of the mirror. A diverging lens (one that is thicker at the edges than the middle) or a concave mirror forms a virtual image. Such an image is reduced in size when compared to the ...

  6. Least distance of distinct vision - Wikipedia

    en.wikipedia.org/wiki/Least_distance_of_distinct...

    The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror.. In optometry, the least distance of distinct vision (LDDV) or the reference seeing distance (RSD) is the closest someone with "normal" vision (20/20 vision) can comfortably look at something. [1]

  7. Reflecting telescope - Wikipedia

    en.wikipedia.org/wiki/Reflecting_telescope

    A convex secondary mirror is placed just to the side of the light entering the telescope, and positioned afocally so as to send parallel light on to the tertiary. The concave tertiary mirror is positioned exactly twice as far to the side of the entering beam as was the convex secondary, and its own radius of curvature distant from the secondary.

  8. Thin lens - Wikipedia

    en.wikipedia.org/wiki/Thin_lens

    The distance between an image and a lens. Real image Virtual image f: The focal length of a lens. Converging lens Diverging lens y o: The height of an object from the optical axis. Erect object Inverted object y i: The height of an image from the optical axis Erect image Inverted image M T: The transverse magnification in imaging (= the ratio ...

  9. Center of curvature - Wikipedia

    en.wikipedia.org/wiki/Center_of_curvature

    A concave mirror with light rays Center of curvature. In geometry, the center of curvature of a curve is a point located at a distance from the curve equal to the radius of curvature lying on the curve normal vector. It is the point at infinity if the curvature is zero. The osculating circle to the curve is centered at the centre of curvature.