Tyndall effect

concept of science on scattering of light

1. Tyndall effect 15251510-010( AROOJ) 15251510-002( KASHIFA)

2. contents History Difference between solution, suspension and colloidal solution Video about this Explanation of tyndall effect Conditions Applications Why sky appear blue? Why sky appear red at sunset and sunrise?

3. Tyndall effect On 19 th century john tyndall introduced it. john tyndall (2 august 1820 –4 December 1893) was a prominent 19 th century physicist and had done several work. visible path of light produced by the scattering action known as tyndall effect.

4. Difference between solution, suspension, colloids. SOLUTION ; when we add solute sugar into solvent water it completely dissolved . It forms the homogeneous mixture It is not able to scatter any light that’s why can’t see any path of light Size of particles in solution is less than 1nm

5. Suspension When add chalk powder into water its particles are insoluble. They are big enough to scatter the light passing through them. “ this effect of scattering of light is called tyndall effect ’’ this solution is heterogeneous mixture. Here we can not observe tyndall for long duration

6. Colloid when we add milk into water .we form colloidal solution By naked eyes it is homogeneous mixture Under electron microscope it is heterogeneous That’s why we observe the tyndall effect here for long duration Size of colloid particles are about 1nm-100nm

7. Conditions Diameter of dispersed particles should be smaller than the wavelength of light used Refractive index of dispersion medium and dispersed phase must be differ greatly in magnitude.

8. Tyndall effect When the light fall from any medium to any colloidal particles and getting interact with it. Consider the light ray falling in colloidal particle through tyndall cone Size of particles around 10nm -100nm After interacting with light reflected in all around And perfectly scattered Colloidal particle seen under the electron microscope

9. Tyndall effect

10. Scattering of light help to see the path of light that is called tyndall effect Path of light ray can not be seen in true solution Path of light ray can be seen in colloidal solution

11. APPLICATIONS Blue color of sky and sea Twinkling of star Visibility of tail of comets Light comes from projection

12. Lord Rayleigh scattering 1871 he discovered wavelength larger less scattering Wavelength less, greater scattering  

13. Why does sky appear blue?

14. Why does sky color turn to red at sun rise and sun set?