Basic principles of light control

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

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

3. Light T he 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 A bsorption

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 r eflection 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

12. Law of refraction Snells law is the law of refraction : N1 sinѲ1 = N2 sinѲ2 N1 is the refractive index of air N2 is the refractive index of glass Ѳ1 is the incident angle of light Ѳ2 is the refracted angle N N for air is 1.000293  

13. 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

14. 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 :

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

16. 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.

17. Thank you