The document discusses the Tyndall effect, which is the scattering of light by colloidal particles or molecules in a suspension, causing the light path to be visible. It provides: 1) A brief history of the Tyndall effect and its discovery by John Tyndall in the 19th century. 2) An explanation of the differences between solutions, suspensions, and colloids, and how the Tyndall effect can be observed in colloids due to their particle size of 1-100nm. 3) Applications of the Tyndall effect including why the sky appears blue and red at sunrise/sunset.

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 19th century john tyndall introduced it.
 john tyndall (2 august 1820 –4 December 1893) was a
prominent 19th 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

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

9. 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

10. TYNDALL EFFECT

12. 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

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

14. LORD RAYLEIGH SCATTERING
1871 he discovered
 𝐼∞ 1/𝜆4
 wavelength larger less scattering
Wavelength less, greater scattering

15. WHY DOES SKY APPEAR BLUE?

16. WHY DOES SKY COLOR TURN TO
RED AT SUN RISE AND SUN SET?