Light is a form of energy . Light help us to see thing around . we can see non luminous object because they reflect light into our eyes
Reflection Of Light:
The bouncing back the light rays which fall on the surface of an object is called reflection of light
The best metal for reflector of ligth is Silver
iii) A bundle of light ray is called beam of light 
Incident ray: The light ray which fall on the surface is known as incident ray
Reflected ray The light ray which bounce back from the surface is know as reflected rays
Normal An imaginary line produce when light ray which fall on the surface is known as normal
Angle of incident rayAn angle produce by incident ray with normal at the point of incidence is know as angle of incident
Angle of reflectionAn angle produce by reflected ray with normal at the point of incidence is know as angle Reflected
Laws of Reflection
i)First Laws of Reflection The incident ray, the normal to the mirror at the
point of incidence
and the reflected ray, all lie in the same plane.
ii)Second Laws of
Reflection The angle of incidence is equal to the angle of reflection
Note: Law of reflection is apply all kind of mirror (plane ,sperical mirror)
Regular reflection When parallel rays remain parallel after reflection in one
direction 
Diffuse reflectionA parallel ray of incident light is reflected in different
direction 
Real image A images which can be obtain on a screan are know as real image
Virtual image A images which can not be obtain on a screan are know as virtual image
Image formation by a plane mirror
i)The image formed by a plane mirror is always virtual and erect.
ii)Object and image are equidistant from the mirror
iii)The image is laterally inverted.
Concave mirrorA spherical mirror, whose reflecting surface is curved
inwards,
that is, faces towards the centre of the sphere, is called a concave mirror. Convex mirrorA spherical mirror whose reflecting surface is curved
outwards, is called
a convex mirror Pole(P)The centre of the reflecting surface of a spherical
mirror is a point called the pole. Centre of curvature(C)The reflecting surface of a spherical mirror has
a centre. This point is called the centre of curvature of
the spherical mirror. Radius
of curvatureThe radius of the sphere of which the
reflecting surface of a spherical mirror forms a part, is called the radius
of curvature of the mirror Principal Focus A point on the principlal axis of a spherical mirror
where the rays of light parallel to the principal axis meet or appear to meat after the reflection
from the mirror Focal Lenght The distance between principal focus and pole . it is
denoted by f Image Formation by Spherical Mirrors Representation of Images Formed by Spherical
Mirrors Using Ray Diagrams Image formation by Concave Mirrors Uses of concave mirrors Image formation by a Convex Mirror Uses of convex mirrors Sign Convention for Reflection by Spherical MirrorsSPHERICAL MIRRORS:
The mirrors, whose reflecting surfaces
are spherical, are called spherical mirrors. The spherical mirrors are the two type :
i) Concave mirror
i)Concave mirrors are commonly used in
torches, search-lights and
vehicles headlights to get powerful parallel beams of light
ii) Concave mirrors are
often used as shaving mirrors to see a larger image of the face
iii)Large concave mirrors are
used to concentrate sunlight to produce
heat in solar furnaces
iv). The
dentists use concave mirrors to see large images of the teeth of patients
i)Convex mirrors are commonly used as
rear-view (wing) mirrors in
vehicles.
ii) Big convex mirror are used as shop and railway station security mirror
According to Cartesian Sign
Convention
(ii) All distances parallel to the principal axis are measured from the
pole of the mirror.
(iii) All the distances measured to the right of the origin
are taken as positive while those measured to the left of
the origin are taken as negative.
(iv) Distances measured perpendicular to and above the principal axis
(along + y-axis) are taken as positive.
(v) Distances measured perpendicular to and below the principal axis
(along –y-axis) are taken as negative
Mirror Formula:
where , u =Object distance
v =Image distance
f= focal length
Note: value of object always taken as negetive
Magnification the ratio of the height of the image to the height of the object are known as magnification
Magnification =m=
The magnification m is also equal to the ratio object distance (u) and image distance (v). Magnification = -
m = -
Note: Negative sign of mgnification indicates that the image is real. and positive indicate image is virtual
REFRACTION OF LIGHT
The change in direction of light when it pass from one medium to another medium is known as refraction
of light
In case of refraction, The angle of incidence is not equal to angle of refraction
Laws of refraction of light
(i) The incident ray, the refracted ray and
the normal to the
interface of two transparent media at the point of incidence, all
lie in the same plane.
(ii) The ratio of sine of angle of incidence to the sine of angle of
refraction is a constant, for the light of a given colour and for
the given pair of media. This law is also known as Snell’s law of
refraction.
This constant value is called the refractive index of the second medium with respect to the first.
The Refractive IndexThe ratio of the speed of light in medium 1 and the speed of light in medium 2.
n21=Refraction by Spherical Lenses
Image Formation by Lenses
Concave
Image Formation in Lenses Using Ray Diagrams
Convex
Lens Formula
Magnification
Magnification =m=
The magnification m is also equal to the ratio object distance (u) and image distance (v). Magnification =
m =
Power of a Lens (P)
The ability of a lens to converge or diverge
light rays depends on its focal length
SI unit of powerThe SI unit of power of a lens is ‘dioptre’. It is denoted by the letter D.
The power of a convex lens is positive and that of a concave lens is negative