1. Light

2. 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 suddurocks@yahoo.in 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.

3. Contents :
 Light
 Laws of Reflection
 Regular & Diffused Reflection
 Luminous & Non – Luminous
Objects
 Real & Virtual Images
 Power of Accommodation

4.  Least Distance of Distinct Vision
 Short – Sightedness
 Long – Sightedness
 Persistence of Vision
 Perception of Colour
 Fascinating Facts
 Some Interesting Pictures

5. 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.

6. 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.

7. • 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. Short – Sightedness
 Myopia or Short Sightedness
means a person can see only
nearby objects clearly, but cannot
see distant objects.
 This defect is removed by using a
concave lens.

14. 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.

15. 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.

16. 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.

17. 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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100. Thank You !!!
Compiled By :
Sudarshan . S . K .
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Improvement To :
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