A curved mirror is one with a surface that is not flat.
A spherical mirror is a mirror in which the surface is a section of a sphere.
A cylindrical mirror is one in which the surface is a section of a cylinder.
A concave mirror, or converging mirror, is a mirror that allows parallel light rays to be reflected at a single point, the focus.
You can recognize a concave mirror by its hollow surface, like the one of a spoon.
A convex mirror, or diverging mirror, is a mirror that moves the reflected rays away from the mirror after they have reached it.
You can recognize a convex mirror by its rounded surface, like the back of a spoon.
The vertex of the mirror (V) is the point of intersection between the principal axis and the mirror.
The focus of the mirror (F) is the point where all the reflected rays (in a converging mirror) or all the extensions of the reflected rays (in a diverging mirror) cross.
The focal length (fl) represents the distance between the vertex of the mirror and its focus.
The centre of curvature of the mirror (C) is the point corresponding to the centre of the circle from which the curved mirror was formed.
The ray of curvature (R) represents the distance between the vertex and the centre of curvature.
The principal axis is a straight line passing through the focus and the centre of curvature.
These elements are represented in the diagram below. Although the elements have been represented in a converging mirror, the same ones also exist in the diverging mirror.
Note: Image in English coming soon
In curved mirrors, the ray of curvature is always twice the focal length.
|R=2times l_f|
To be able to draw the image associated with an object in front of a curved mirror, you first need to understand the behaviour of the three main rays of curved mirrors. There are three main rays that can be drawn to identify the position of an image.
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When the incident ray is directed parallel to the main axis, it is reflected at the focus. This ray is shown in red in the diagram below.
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When the incident ray passes through the principal focal point, it is reflected parallel to the principal axis. This ray is shown in green in the diagram below.
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When the incident ray passes through the centre of curvature, it is reflected back on itself. This ray is shown in blue in the diagram below.
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When the incident ray is directed parallel to the principal axis, it is reflected so that its extension is directed towards the focus. This light ray is shown in red in the diagram below.
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When the extension of the incident ray is directed towards the focus, it is reflected parallel to the principal axis. This ray is shown in green in the diagram below.
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When the extension of the incident ray is directed towards the centre of curvature, it is reflected back on itself. This ray is shown in blue in the diagram below.
Note: In this image, the extension of the second reflected ray (green dotted line) should be parallel to the principal axis.
The field of vision (or field of view) of a curved mirror is the space that can be perceived by an observer looking into the curved mirror.
The field of vision can be determined using the laws of reflection. Simply follow the steps below to observe the field of vision in a curved mirror.
1. From the observer, draw the rays of light travelling to the ends of the concave mirror.
2. Draw normal lines at each point of incidence. In a concave mirror, all you need to do is draw the rays of curvature, because, by definition, a ray always arrives perpendicular to the surface of a curved mirror.
3. Draw the incident rays using the law of reflection.
4. Everything in between the incident rays is a part of the observer's field of vision.
1. From the observer, draw the rays of light reaching the ends of the convex mirror.
2. Draw normal lines at each point of incidence. In a convex mirror, it is only necessary to draw rays of curvature, because, by definition, a ray always arrives perpendicular to the surface of a curved mirror. However, they need to be extended so that they can act as a normal line.
3. Draw the incident rays using the law of reflection.
4. Everything between the incident rays is a part of the observer's field of view.
The field of vision in a convex mirror is considerably greater than in a concave or plano-convex mirror.
Spherical aberration refers to an aberration in which the rays of light coming from the edge of the mirror and the centre of the mirror are no longer focused at the same point.
In a case of spherical aberration, all the rays reflected by a spherical mirror do not converge at the same point as they should.
To correct this problem, a parabolic mirror can be used. This type of mirror has the ability to bring all the reflected rays to a single point, the focus.
