to the object distance d o in front of the plane mirror. The image formed by the plane mirror for extended object is shown in Figure . (b). .
. Characteristics of the image formed by plane mirror (i) The image formed by a plane mirror is virtual, erect and laterally inverted sidewise (left / right). (ii) The size of the image is equal to the size of the object. (iii) The image distance behind the mirror is equal to the object distance in front of the mirror.
(iv) If an object is placed between two plane mirrors inclined at an angle θ , then the number of images n formed is given in Table . the images formed are shown in Figure . . - - - - Unit ray optics Centre of curvature : The centre of the sphere of which the mirror is a part is called the centre of curvature C of the mirror.
Radius of curvature : The radius of the sphere of which the spherical mirror is a part is called the radius of curvature R of the mirror. Pole : The middle point on the spherical surface of the mirror (or) the geometrical centre of the mirror is called pole P of the mirror (or) optic centre. Principal axis : The line joining the pole P and the centre of curvature C is called the principal axis of the mirror. The light ray travelling along the principal axis towards the mirror after reflection travels back along the same principal axis.
It is also called optical axis Object Image Mirror H H' F' (h +h )/ i1 i2 i2 i1 h1 h / h / h / h / E h2 F If the distance between his head H and eye E is h and distance between his feet F and eye E is h . The person’s total height is, h. Here it is, h = h + h By the law of reflection, the angle of incidence and angle