Spherical mirror A always forms an erect image of an object, so it is a convex mirror and spherical mirror B forms erect as well as inverted image of an object, so it is a concave mirror.
The ray diagrams are as follows:
When incident rays, parallel to the principal axis, then the light reflected will be appeared as coming from focus, and when incident ray moves towards the center of curvature, the reflected ray will return back to the same path. This proves that the reflected rays are diverging and therefore, the mirror always produce a virtual and erect image. So, the mirror is a convex mirror.
Similarly, the nature of the image formed in case of concave mirror, depends on the position of the object.
The ray diagrams are:
When an incident ray is parallel to the principal axis, the reflected ray appears to be coming from the focus and when incident ray moves towards the center of curvature, the reflected ray retraces the path. These two rules show that the reflected rays are diverging and when produced back-wards, the rays appear to meet. Thus, this mirror always produces a virtual image which is always erect. Mirror 'B' is a concave mirror. The nature, position and size of the image formed by a concave mirror depends on the position of the object in relation to points P(Pole), F(focus) and C(center of curvature) of the mirror.
Case 1. When. the object is placed between P and F-the two reflected rays (one passes through the focus and other retraces through center of curvature) are diverging and appear to meet in backward direction. This produces a virtual and erect image.
Case 2. As the object moves away from the mirror beyond F the two reflect rays actually meet below the principal axis which produces a real and inverted image.
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