1. Basic Principles of
Light Control
Submitted To:
Prof G.Nagaraju
Presented By:
K.Archana
100101CSR027
CSE, 8th sem

2. Content
Light
Its characteristics
Basic principles of light
Reflection
Refraction
Diffusion
Absorption

3. Light
The natural agent that stimulates sight and makes things
visible.
Also called visible electromagnetic radiation that is capable of
causing a visual sensation and has wavelengths from about 380
to about 780 nanometres

4. Characteristics
Light is a form of energy produced by luminous objects.
Light can travel through vacuum.
Light can penetrate through transparent materials but cannot
pass through opaque objects.
Light travels in a straight line in an optically homogeneous
medium.
Light bounces back when made to fall on polished surfaces
such as mirrors or metal surfaces. This bouncing back of light
is described as reflection.

5. The change in the velocity of light when it travels from one
transparent medium to another is described as refraction.
Light appears to have a dual nature. During propagation, light
exhibits wave characteristics but when it interacts with
matter, it behaves like particles.

6. Basic Principles of light
There are four methods of light control:
• Reflection
• Refraction
• Diffusion
• Absorption

7. Reflection
When a ray of light falls on any surface, a part of the light is
sent back to the same medium. This phenomenon where the
incident light falling on a surface is sent back to the same
medium is known as reflection.
There are two types of reflection of light:
• Regular reflection
• Irregular reflection

8. Regular reflection
Regular reflection takes place when a ray of light is incident on
a polished smooth surface like a mirror. Here the reflected ray
of light moves only in a fixed direction.
It is also called as Specular reflection.
Incident light Reflected light

9. Irregular reflection
Irregular reflection takes place when a beam of light is incident
on a wall or wood, which is not smooth or polished.
Also called as diffused reflection or scattering of light.

10. Law of Reflection
The angle of incidence is equal to the angle of reflection.
 The ratio reflected light to incident light is known as
reflection factor.

11. Refraction
When a beam of light is passed through a boundary between
two transparent substances having different densities, its
direction is changed.
The light will change its velocity and ‘bend’.
Speed of light in air is very similar to speed of light in a
vacuum

13. Law of refraction
•

14. Diffusion
When light is incident on a rough surface, it is reflected or
transmitted in many directions at once, this is called diffusion
or scattering.
To prevent glare from a light source, a diffusing glass screen
can be introduced between the observer and the light source.
Two types of diffusing glass are employed. They are:
• Opal glass
• Frosted glass

15. Opal glass: ordinary glass made up of a material having
refractive index different from that of a glass
• Eg: milk glass
Frosted glass: produced by coating ordinary glass with a
crystalline substance
• Eg:

16. Absorption
The taking up and storing of energy, such as radiation, light, or
sound, without it being reflected or transmitted.

17. The absorption of light occurs when a ray of light strikes a
surface. The energy from the light is transferred to the surface
material.
During absorption, the energy may change from one form into
another.
An absorbing surface prevents reflection or diffusion of light
striking on the surface.

18. Thank you