Image formation by spherical mirror and …

Spherical mirrors are of two types:

1. Convex mirrors or diverging mirrors in which the reflecting surface is curved outwards.
2. Concave mirrors or converging mirrors in which the reflecting surface is curved inwards.                    Some terms related to spherical mirrors:1. The centre  of  curvature  (C) of  a  spherical  mirror  is  the  centre  of  the hollow  sphere  of  glass,  of which the spherical mirror is a part.

• The radius  of  curvature  (R) of  a  spherical  mirror  is  the  radius  of  the  hollow  sphere  of  glass,  of which the spherical mirror is a part.
• The pole (P) of a spherical mirror is the centre of the mirror.
• The principal axis of a spherical mirror is a straight line passing through the centre of curvature C and pole P of the spherical mirror.
• The principal focus (F) of a concave mirror is a point on the principal axis at which the rays of light incident on the mirror, in a direction parallel to the principal axis, actually meet after reflection from the mirror.
• The principal focus (F) of a convex mirror is a point on the principal axis from which the rays of light  incident  on  the  mirror, in  a  direction  parallel  to  the  principal  axis, appear  to  diverge  after reflection from the mirror.
• The focal length (f) of a mirror is the distance between its pole (P) and principal focus (F).

• For spherical mirrors of small aperture, R = 2f.

  Image formation by Spherical Mirrors: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, F and C. The image formed is real for some positions of the object. It is found to be a virtual image for a certain other position. The image is either magnified, reduced or has the same size, depending on the position of the object.