ACHTUNG: Sie befinden sich im Museum-Online-Archiv 1997. Die Inhalte dieser Seite sind unter Umständen nicht mehr aktuell.ACHTUNG: Sie befinden sich im Museum-Online-Archiv 1997. Die Inhalte dieser Seite sind unter Umständen nicht mehr aktuell. |
When we see an object, light that comes from the object goes into our eyes. If the object is a light source, the light originates from the object. If the object is not a light source, light that comes from a light source (e.g. from the sun) reflects from the object into our eyes. |
| We see the object where the light seems to be coming from. If the light reflects from a mirror surface before it goes into our eyes, we see an image of the object behind the mirror. |  |
| Reflected rays from the same object can be traced back to a single point behind the mirror. The image of the object is the same size and the same distance behind the mirror as the object is in front. This kind of image where the rays have to be traced back is called a virtual image. |  |
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The image in a plane mirror is upright but laterally inverted. This means that the left and right sides are swapped round, but not top and bottom. |
| Light rays are reflected twice from a right angled mirror. If an incident ray is parallel to the ground, the reflected ray is parallel to the incident ray. |  |
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Like the image in a plane mirror, the image in a right angled mirror is virtual, upright, and the same size. |
| In contrast to the image in a plane mirror, the image in a right angled mirror is not laterally inverted. |  |
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Each ray that hits a curved mirror obeys the laws of reflection. |
| Incident rays that are parallel to the optical axis (the axis of symmetry of the mirror) converge to a single point after hitting the mirror. This point is called the focus. Its distance from the vertex of the mirror is called the focal length. |  |
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If an object is located within the focal length, its image is virtual, upright, and enlarged. |
| If an object is placed outside the focal length but still
within the double focal length, its image is real,
upside-down, and enlarged.
A real image is one where the reflected rays actually cross. They do not have to be traced back. A real image can be projected onto a screen. |
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If an object lies outside the double focal length, its image is real, upside-down, and small. |
| The laws of reflection also apply for the reflection from convex mirrors. |  |
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Rays that come into a convex mirror diverge after reflection. If the incident rays are parallel to the optical axis, the reflected rays seem to emerge from a point behind the mirror. This point is called the focus of the convex mirror. |
| The image in a convex mirror is always virtual, upright, and small. |  |
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The reflecting surface of a cylindrical mirror is curved
outwards only in one direction. Therefore, the cylindrical mirror works
like a convex mirror in one direction and like a plane mirror in the
other direction.
It is a most intriguing experience to view an anamorphotic picture in a cylindrical mirror. Anamorphotic pictures are distorted in such a way that you see the undistorted pictures when you view them in a cylindrical mirror. |
| Even more fascinating are the distortions in conical mirrors. When you see an anamorphotic picture that is designed for viewing in a conical mirror, you can hardly guess what it shows. |  |
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