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scattering of light.ppt

  1. A seminar presentation on - Scattering of light Presented by- Dilip Bhuyan Roll no-125 B.Sc 4th Semester Department of Physics, Bahona College
  2. Table of content  Introduction  History on scattering of light  How the light scattered  Types of scattering of light  Phenomenon of scattering of light • Blue colour of sky • White colour of clouds or fog • Danger signal Red • Sun & sky looks Red at sunrise & sunset  Conclusion  References 3/20/2023 7:31:12 AM 2
  3. Introduction Scattering of light is the phenomenon of change in the direction of light on striking a particular type of particle.  The phenomenon of scattering of light by smoke, dust, water droplets and colloidal particles(1nm-1000nm) is known as Tyndall effect.  Making the path of light visible. 3/20/2023 7:31:12 AM 3  Scattering of light happen only because of the electromagnetic interaction among photons and the particles of medium.  It must be the size of the particle is smaller then the wavelength of the incident light
  4.  In 1928, Sir C.V Ramman discovered that when a beam of coloured light entered a liquid, a fraction of light scattered by liquid in different colour, which is known as Ramman effect. History on light scattered  In 1870 , John Tyndall first give the concept of scattering of light 3/20/2023 7:31:12 AM 4  In 1871, Lord Rayleigh first noticed this light scattering.
  5. How the light scattered  Random reflection from a rough surface-  As the surface has more roughness absorbs more energy from the light ray and it will scatter in different direction depending on the wavelength of light ray.  Reflection through impurities present in volume-  When light is scattered by charged particle by levelling the energy of the incident radiation and the rest energy of the charged particle present. 3/20/2023 7:31:12 AM 5
  6. Types of scattering of light 1. Rayleigh or selective scattering 3/20/2023 7:31:12 AM 6 • It is an elastic scattering( i.e. wavelength of the scattered light is same as the incident light). •Occurs when the radius of the scattering object is much smaller then the wavelength of light i.e. r<< λ •Shorter wavelength scattered much more then the longer wavelength i.e. I∝ λ-4 •Blue sky in a sunny day is an example of this type of scattering.
  7. 3/20/2023 7:31:12 AM 7 2. Mie scattering • Particle dimension comparable to wavelength of radiation. • It is also an elastic scattering . • The clouds having water droplets look white is an example of this type of scattering. 3. Electromagnetic scattering- • It includes both the elastic light and inelastic light scattering . Electric light scattering includes-Rayleigh scattering & mie scattering. Inelastic scattering includes-Compton scattering, Ramman scattering etc.
  8. 3/20/2023 7:31:12 AM 8 Phenomenon of light scattering
  9. 3/20/2023 7:31:12 AM 9 3. Red colour as a danger signal o Wavelength of red colour is large , so it less scattered and travel long distance. 2. White colour of clouds or fog o Large particle scatter large wavelength. o Scattered all the incident ray & it appears in our eyes as white.
  10. 3/20/2023 7:31:12 AM 10 Conclusion Scattering theory is important as it underpins one of the most ubiquitous tools in physics, almost everything we know about nuclear and atomic physics has been discovered by scattering experiment, e.g. Rutherford’s discovery of the nucleus, the discovery of sub atomic particles (such as quarks), etc.
  11. 3/20/2023 7:31:12 AM 11 References   www.//  Internet  Reference books  A textbook of optics, by Dr. N. Subrahmanyam & Brijlal  New simplified physics, by S.L Arora
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