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
7.
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
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