light
TRANSCRIPT
L i g h t
Acknowledgement
• Information and pictorial illustrations to create this
work have been drawn from class notes, prescribed
text books and various internet resources. The
author gratefully acknowledges the same. Any
objections to the use of internet resources may
please be indicated to [email protected] so that the
same can be removed from the illustrations used in
this file.
• This presentation is created with the sole intention
of benefitting a large number of student community.
This may not be used for any commercial purpose.
Contents :
Light
Laws of Reflection
Regular & Diffused Reflection
Luminous & Non – Luminous Objects
Real & Virtual Images
Power of Accommodation
Least Distance of Distinct Vision
Short – Sightedness
Long – Sightedness
Persistence of Vision
Perception of Colour
Fascinating Facts
Some Interesting Pictures
Light
Light is a form of energy.
Light travels in a straight line.
Light enables us to see the objects
around us.
The light reflected from objects falls into
our eyes & thus, we can see the
objects.
Dispersion of light is splitting of white or
some other light into its components.
Laws of Reflection
The light ray which strikes any surface
is called the Incident Ray.
The ray that comes back from the
surface after reflection is known as the
Reflected Ray.
The perpendicular to the surface at the
point of incidence is known as Normal.
• The angle between the normal
and incident ray is called the
Angle of Incidence.
• The angle between the normal
and the reflected ray is known
as the Angle of Reflection.
• The angle of incidence is
always equal to the angle of
reflection.
• This is known as the Law of
Reflection.
Regular & Diffused Reflection
Reflection from a smooth surface
like that of a mirror is called
Regular Reflection.
When all the parallel rays reflected
from a plane surface are not
parallel, the reflection is known as
Diffused or Irregular reflection.
Luminous & Non – Luminous Objects
• Those objects which emit their own
light are called Luminous Objects.
• The objects which do not emit light of
their own, but they reflect light falling
on them, are called Non – Luminous Objects.
Real & Virtual Images
The image formed when incident rays
after reflection actually meet at a
point is known as a Real Image.
The image formed when incident ray
after reflection do not actually meet,
but appear to meet at a point is
knows as a Virtual Image.
Power of Accommodation
The ability of the eye to focus the
distant objects as well as the
nearby objects at the retina by
changing the focal length or
converging power of its lens is
known as the Power of
Accommodation.
Least Distance of Distinct Vision
The minimum distance at which an
object must be placed so that a
normal eye may see the object
clearly without any strain on the eye
is known as the Least Distance of
Distinct Vision.
It is about 25cm for a normal eye.
Short – Sightedness
Myopia or Short Sightednessmeans a person can see only nearby objects clearly, but cannot see distant objects.
This defect is removed by using a concave lens.
Long – Sightedness
Hypermetropia or Long –Sightedness is the reverse of Myopia.
A person suffering from this defect can see distant objects clearly, but not nearby objects.
The defect is removed by using convex lens.
Persistence of Vision
Impression of an image on the retina lasts for 0.1 sec after the removal of the object.
This effect is known as Persistence of Vision.
Perception of Colour
The human eye contains a large number of cell rods and cones which are sensitive to light.
The rods respond to the intensity of light and the cones respond to the colour of the light.
If cone cells are absent in the eye, then such a person is Colour Blind.
Fascinating Facts
A ray of light is an idealisation.
In reality, we have a narrow
beam of light which is made
up of several rays.
For simplicity, we use the term
ray for a narrow beam of light.
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Thank You !!!
Compiled By :
Sudarshan . S . K .
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