¤ If the reflecting surface of the mirror is spherical, then the mirror is called a spherical mirror.
¤ Spherical mirrors are of two types
i) Convex mirror ii) Concave mirror
¤ A spherical mirror whose reflecting surface is curved outwards is called convex mirror.
¤ A beam of light generally diverges after reflecting form its surface, hence it is called divergent mirror also.
¤ A spherical mirror whose reflecting surface is curved inwards is called concave mirror.
¤ A beam of light generally converges after reflection from its surface, hence it is called convergent mirror also.
¤ The centre of sphere of which the given spherical mirror is a part is called the centre of curvature. It is denoted by 'C'.
¤ The centre of spherical mirror is called pole or vertex. It is denoted by 'P'.
¤ The line drawn or passes through the centre of the mirror (pole) is called optical axis or principal axis.
¤ All the light rays which are parallel to principal axis, are converge at a point after reflection from the mirror is called focal point (or) focus 'F'.
¤ The distance between focus and pole of mirror is focal length (f).
¤ The distance between Pole (P) and centre of Curvature (C) is Radius of curvature (R).
¤ Relation between 'R' and 'f' is 
(or) f = 
¤ Images formed by a concave mirror
|
Position of the object |
Position of the image |
Enlarged/ Diminished |
Inverted/ Erected |
Real/ Virtual |
|
Between mirror and F |
Behind the mirror |
Enlarged | Erected | Virtual |
|
On Focal point |
At infinity |
- | - | - |
|
Between F and C |
Beyond C |
Enlarged |
Inverted |
Real |
|
On Centre of curvature |
On C |
same size |
Inverted | Real |
|
Beyond C |
Between F and C |
Diminished | Inverted |
Real |
¤ Images formed by a convex mirror.
|
Position of the object |
Position of the image |
Enlarged/ Diminished |
Inverted/ Erected |
Real/ Virtual |
|
Between mirror and F |
Behind the mirror |
Diminished |
Erected |
Virtual |
|
On Focal point |
Between P and F |
Diminished |
Erected |
Virtual |
|
Between F and C |
Between P and F |
Diminished |
Erected |
Virtual |
|
On Centre of curvature |
Between P and F |
Diminished |
Erected |
Virtual |
|
Beyond C |
Between P and F |
Diminished | Erected | Virtual |
¤ The image formed by controlled rays of reflection is called virtual image. It cannot be caught on screen.
¤ The image formed by actual intersection of reflection rays is called real image. This can be caught on screen.
¤ Mirror formula 
f - Focal length of the spherical mirror
u - Object distance
v - Image distance
¤ Sign convention for the parameters related to the mirror equation.
i) All distances should be measured from the pole.
ii) The distances measured in the direction of incident light, to be taken positive and those measured in the direction opposite to incident light to be taken negative.
iii) Height of object (ho) and height of image (hi) are positive if measured upwards from the axis and negative of measured downwards.
¤ Summary of cartesian sign convention
22. A big concave mirror is used to make a solar cooker. It works on the Principle of converging of sunlight at a point (F) due to concave mirror.
23. Uses of convex mirrors
i) Side view mirrors in vehicles
ii) Big convex mirrors are used as shop security mirrors.
24. Uses of concave mirrors
i) Mirror used by dentists ENT specialists used as a head mirror.
ii) Used as shaving mirror
iii) As a reflector in head light of vehicles.
iv) Used in search lights, telescopes
v) Used in solar equipments.
Reflection of light at curved surfaces
Conceptual Flow chart:
