Real image: Difference between revisions
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{{Short description|Collection of focus points made by converging light rays}} | {{Short description|Collection of focus points made by converging light rays}} | ||
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[[File:Real image.svg|thumb|right| Top: The formation of a real image using a convex lens. Bottom: The formation of a real image using a concave mirror. In both diagrams, ''f'' is the [[Focus (optics)|focal point]], ''O'' is the object, and ''I'' is the image. Solid blue lines indicate light rays. It can be seen that the image is formed by actual light rays and thus can form a visible image on a screen placed at the position of the image.]] | [[File:Real image.svg|thumb|right| Top: The formation of a real image using a convex lens. Bottom: The formation of a real image using a concave mirror. In both diagrams, ''f'' is the [[Focus (optics)|focal point]], ''O'' is the object, and ''I'' is the image. Solid blue lines indicate light rays. It can be seen that the image is formed by actual light rays and thus can form a visible image on a screen placed at the position of the image.]] | ||
[[File:Convex lens (magnifying glass) and upside-down image.jpg|thumb|341x341px|An inverted real image of distant house, formed by a convex lens, is viewed directly without being projected onto a screen.]] | [[File:Convex lens (magnifying glass) and upside-down image.jpg|thumb|341x341px|An inverted real image of distant house, formed by a convex lens, is viewed directly without being projected onto a screen.]] | ||
[[File:realimageondetector.svg|thumb|384px|right|Producing a real image. Each region of the detector or retina indicates the light produced by a corresponding region of the object.]] | |||
[[ | In [[optics]], an ''image'' is defined as the collection of [[Focus (optics)|focus point]]s of [[ray (optics)|light rays]] coming from an object. A '''real image''' is the collection of focus points actually made by converging/diverging rays, while a [[virtual image]] is the collection of focus points made by extensions of [[Beam divergence|diverging]] or converging rays.<ref>{{Cite web |title=Images, real and virtual |url=https://web.pa.msu.edu/courses/2000fall/phy232/lectures/lenses/images.html |access-date=18 November 2025}}</ref> In other words, a real image is an image which is located in the plane of convergence for the light rays that originate from a given object. Examples of real images include the image produced on a [[Photodetector|detector]] in the rear of a [[camera]], and the image produced on an eyeball [[retina]] (the camera and eye focus light through an internal convex lens).<ref>{{Cite web |title=Difference Between Real Image and Virtual Image |url=https://byjus.com/physics/difference-between-real-image-and-virtual-image/ |access-date=18 November 2025 |website=byjus.com}}</ref> | ||
In | In simple terms, a real point image is formed when all the rays of light from a point object passing through an optical system converge at a single point and a virtual point image is formed when all the rays of light from a point object passing through an optical system seem to come from a single point.<ref>Essential Principles of Physics, P M Whelan and M J Hodgson, John Murray 1979, p. 234.</ref> | ||
In ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines; perceived or extrapolated rays of light are represented by dashed lines. A real image occurs at points where rays actually converge, whereas a virtual image occurs at points that rays appear to be diverging from. | In ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines; perceived or extrapolated rays of light are represented by dashed lines. 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 mirror]]s and [[Convex Lens|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 approaches the focal point the image approaches infinity, and when the object passes the focal point the image becomes virtual and is not inverted (upright image). The distance is not the same as from the object to the lenses. | Real images can be produced by [[concave mirror]]s and [[Convex Lens|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 approaches the focal point the image approaches infinity, and when the object passes the focal point the image becomes virtual and is not inverted (upright image). The distance is not the same as from the object to the lenses.<ref>{{Cite web |title=Lenses - AQA: Real and virtual images |url=https://www.bbc.co.uk/bitesize/guides/zt7srwx/revision/2 |access-date=18 November 2025 |website=BBC}}</ref> | ||
Real images may also be inspected by a second lens or lens system. This is the mechanism used by [[optical telescope|telescope]]s, [[binoculars]] and [[light microscope]]s. The objective lens gathers the light from the object and projects a real image within the structure of the optical instrument. A second lens or system of lenses, the [[eyepiece]], then projects a second real image onto the retina of the eye. | Real images may also be inspected by a second lens or lens system. This is the mechanism used by [[optical telescope|telescope]]s, [[binoculars]] and [[light microscope]]s. The objective lens gathers the light from the object and projects a real image within the structure of the optical instrument. A second lens or system of lenses, the [[eyepiece]], then projects a second real image onto the retina of the eye. | ||
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*[[Lens (optics)|Lens]] | *[[Lens (optics)|Lens]] | ||
*[[Erect image]] | *[[Erect image]] | ||
==References== | |||
{{Reflist}} | |||
[[Category:Geometrical optics]] | [[Category:Geometrical optics]] | ||
Latest revision as of 15:45, 19 November 2025
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In optics, an image is defined as the collection of focus points of light rays coming from an object. A real image is the collection of focus points actually made by converging/diverging rays, while a virtual image is the collection of focus points made by extensions of diverging or converging rays.[1] In other words, a real image is an image which is located in the plane of convergence for the light rays that originate from a given object. Examples of real images include the image produced on a detector in the rear of a camera, and the image produced on an eyeball retina (the camera and eye focus light through an internal convex lens).[2]
In simple terms, a real point image is formed when all the rays of light from a point object passing through an optical system converge at a single point and a virtual point image is formed when all the rays of light from a point object passing through an optical system seem to come from a single point.[3]
In ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines; perceived or extrapolated rays of light are represented by dashed lines. 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 approaches the focal point the image approaches infinity, and when the object passes the focal point the image becomes virtual and is not inverted (upright image). The distance is not the same as from the object to the lenses.[4]
Real images may also be inspected by a second lens or lens system. This is the mechanism used by telescopes, binoculars and light microscopes. The objective lens gathers the light from the object and projects a real image within the structure of the optical instrument. A second lens or system of lenses, the eyepiece, then projects a second real image onto the retina of the eye.
See also
References
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