Basic principles of light control


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Basic principles of light control

  1. 1. Basic Principles of Light Control Submitted To: Prof G.Nagaraju Presented By: K.Archana 100101CSR027 CSE, 8th sem
  2. 2. Content Light Its characteristics Basic principles of light Reflection Refraction Diffusion Absorption
  3. 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. 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. 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. 6. Basic Principles of light There are four methods of light control: • Reflection • Refraction • Diffusion • Absorption
  7. 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. 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. 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. 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. 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. 12. Law of refraction •
  13. 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. 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. 15. Absorption The taking up and storing of energy, such as radiation, light, or sound, without it being reflected or transmitted.
  16. 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. 17. Thank you