2. 1.Introduction about light:-
i) Light is a form of energy which helps us to see objects.
ii) When light falls on objects, it reflects the light and when the reflected light reaches our
eyes then we see the objects.
9. • A plane mirror is a mirror with a flat reflective surface.
• Image formed by a plane mirror is always virtual and erect.
• The size of image is equal to that of object.
• The image formed is as far behind the mirror as the object is in front
• The image is laterally inverted.
10. Spherical mirror:-
A spherical mirror is a curved mirror which is part of a hollow sphere.
Spherical mirror has two types:-
1) Concave mirror-
A spherical mirror whose reflecting surface is curved inwards is called
11. 2) Convex mirror-
A spherical mirror whose reflecting surface is curved outwards is called
13. Pole (P)- the centre of reflecting surface of a spherical mirror is a point
Centre of curvature (C)- the reflecting surface of a spherical mirror forms a
part of a sphere. Centre of this sphere is called centre of curvature.
centre of curvature is not a part of mirror. The centre of curvature of
a concave mirror lies in front of it and it lies behind the mirror in convex mirror.
Radius of curvature (R)- the radius of the sphere of which reflecting surface
of a spherical mirror forms a part is called radius of curvature of mirror.
Principal axis- straight line passing through the pole and centre of curvature
of spherical mirror is called principal axis.
14. Principal focus(F)- In a concave mirror, rays of light parallel to the principal axis after
reflection meet at a point on the principal axis called principal
In a convex mirror, rays of light parallel to the principal axis after
reflection get diverged and appear to come from a point on the
principal axis behind the mirror called principal focus (F).
15. Focal length(f)- It is the distance between the pole and
In a spherical mirror the radius of curvature is twice the
R = 2f or f = R/2