Reflection and Refraction of light presentation free. In this presentation I've explained these phenomenon in very detailed and very informative presentation.

2. Group Members
 Alishba Naveed (BCS-21003)
 Fajar Nadeem (BCS-21005)
 Subhan Shahid (BCS-21020)
 Ayesha Sadiqa (BCS-21004)

3. Refraction & Reflection of Light

4. Main Objectives of Refraction:
Definition of Refraction Refractive Index
Causes of Refraction
Critical Angle
Applications of
Refraction
Uses of Refraction in
daily life

5. Refraction
 Definition :
“Refraction is the bending of a wave when it passes from one medium to another medium”
 The bending is caused due to the difference in density between the two substances.

6. Causes of Refraction
 The cause of the refraction of light is that light travels at different speeds in
different media. This change in the speed of light when it moves from one
medium to another causes it to bend.
 This change in speed is caused due difference to difference in optical densities
of the mediums

7. Refractive index
 Refractive index, also called index of refraction, measure of the
bending of a ray of light when passing from one medium into
another. If I is the angle of incidence of a ray in vacuum and r
is the angle of refraction
 Refractive index is also equal to the velocity of light c of a
given wavelength in empty space divided by its velocity v in a
substance or n = c/v.

8. Critical Angle
 “In Optics, the angle of incidence to which the angle of refraction is 90° is
called the critical angle.”

9. Laws of Refraction
 The angle of incidence is the angle between the incident ray and the normal; denoted as ‘i’.
The angle of refraction is the angle between the refracted ray and the normal; denoted as ‘r’.
Laws of refraction are :
 The incident ray, reflected ray and the normal, to the interface of any two given mediums; all
lie in the same plane.
 The ratio of the sine of angle of incidence to the sine of angle of refraction is constant. This
is also known as Snell’s law of refraction
𝐬𝐢𝐧 𝒊
𝐬𝐢𝐧 𝒓
= constant

10. Applications of Refraction
Refraction has many applications in optics and technology. A few of the
prominent applications are :
 A lens uses refraction to form an image of an object for various purposes, such
as magnification.
 Spectacles worn by people with defective vision use the principle of refraction.

11. Refraction in Peephole
 Refraction is used in peepholes of house doors, cameras, movie
projectors and telescopes.

12. Refraction of light in real life
 A swimming pool always looks shallower than it really is because the
light coming from the bottom of the pool bends at the surface due to
refraction of light.
 Formation of a rainbow is an example of refraction as the sun rays
bend through the raindrops resulting in the rainbow.

13. Refraction through Prism
 When white light passes through a prism it is split into its component colors – red,
orange, yellow, green, blue and violet due to refraction of light.

14. Main Objectives of Reflection:
Examples of
Reflection
Definition of
Reflection
What is the Reflection
of Light?
How Reflection of
Light occurs?
Laws of Reflection
of Light
Types of Reflection
Examples in daily
life

15. Reflection of
Light
Definition:
“When light
travelling in a certain
medium falls on the
surface of another
medium, a part of it
returns back in the
same medium”.

16. Example of Reflection
Reflection of Light in water pool
Reflection also takes place in water. If
anyone see in the water, then an image of
that person get virtual into the surface of
water……
Lightning of moon at night
Moon is lightning not because of its own
light. It is glowing because it reflects light
waves coming from the sun……

17. What is Reflection of light?
 To begin with, the reflection of light occurs whenever a ray of light falls on a smooth polished surface
and bounces back. In other words, the ray of light approaching any surface results in the reflection of
light. Further, the ray of light which falls on the surface is known as an Incident ray while the ray of light
which gets reflected back is called a Reflected ray. Also, if a perpendicular is to be drawn between the
two rays on the reflecting surface, it is known as Normal.

18. What is Reflection of Light?
 Incident Ray:
It is the ray that falls on the surface.
 Reflected Ray:
The ray which is reflected from the surface.
 Normal:
Perpendicular on the polished surface.
i = Incident Ray
r = Reflected Ray

19. How Reflection of
Light occurs?
Reflection occurs when
light travelling through
one material bounces off
the different material. The
reflected light still travels
in a straight line, only in
a different direction. The
light is reflected at a
same angle that is hits
the surface. The angle of
incidence is equal to
the angle of reflection.
i = Angle of Incidence
r = Angle of Reflection

20. Laws of
Reflection of
Light
The law of reflection states
that:
 The incident ray, the
reflected ray and the
normal all lie in the same
plane.
 The angle of incidence =
The angle of reflection
θi = θr

21. Three Types of Reflection
Specular Reflection/
Regular Reflection
Diffuse Reflection/
Irregular Reflection
Multiple Reflection

22. Specular Reflection
Definition:
“When a parallel beam of light falls on a smooth and highly
polished surface, then the reflected beam is also parallel
and directed in a fixed direction. Such reflection of light is
called regular reflection”.
Example:
Search lights and automobiles headlights are the
examples of regular reflection of light.

23. Diffused Reflection
Definition:
“When a parallel beam of light falls on a rough surface, then the reflected light is not parallel but
spread over a wide area. Such reflection of light is called diffused reflection”.
Example:
Light reflected from the wooden table, newspaper etc, is the example of diffused reflection of
light.

24. Multiple Reflection
Definition:
“When two mirrors are kept inclined at an angle, they can together form multiple images.
This is because the image formed by one mirror forms the object for the other mirror”
Example:
Multiple reflection are used in periscopes. Periscope are used in submarines and war
tanks to see the objects directly.

25. “
”
Number of Images = ( 360˚/ x ) -1
Where x= angle b/w mirrors
Angle b/w the mirrors No. Of images
45˚ 7
60˚ 5
90˚ 3
120˚ 2
180˚ 1
0˚ – parallel to each other Infinite numbers

26. Examples in daily life
Blue Sky
The Blue Sky is because light hits
different particles in the atmosphere
& scatters in all directions. Since
blue has a smaller wavelength than
Red, it is scattered more than red.
That’s why the sky looks blue……
Sunset is Red
The Sunset is Red because
when the sunset happens, the
sky has already scattered most
of the blue light as it has
travelled around the atmosphere
since the day. So, the red light
dominates during a sunset.
Clouds look White
Clouds look White because the
cloud’s water droplets are much
larger than the wavelength of light.
So, all the colors get scattered in
different directions to create white
color.