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Guiding Rays: Image Formation with Spherical Mirrors:
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- Any two of the following rays can be considered for locating the image.
- (i) A ray parallel to the principal axis, after reflection, will pass through the principal focus in case of a concave mirror or appear to diverge from the principal focus in case of a convex mirror.
- (ii) A ray passing through the principal focus of a concave mirror or a ray which is directed towards the principal focus of a convex mirror, after reflection, will emerge parallel to the principal axis.
- (iii) A ray passing through the centre of curvature of a concave mirror or directed in the direction of the centre of curvature of a convex mirror, after reflection, is reflected back along the same path.
- The light rays come back along the same path because the incident rays fall on the mirror along the normal to the reflecting surface.
- (iv) A ray incident obliquely to the principal axis, towards a point P (pole of the mirror), on the concave mirror or a convex mirror is reflected obliquely.
- The incident and reflected rays follow the laws of reflection at the point of incidence (point P), making equal angles with the principal axis.
- In all the above cases the laws of reflection are followed.
- At the point of incidence, the incident ray is reflected in such a way that the angle of reflection equals the angle of incidence.
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