Briefly describe an experimental arrangement for observing scattering of light in colloidal solution.

Briefly describe an experimental arrangement for observing scattering

1.	Briefly describe an experimental arrangement for observing scattering of light in colloidal solution.
Answer» Solution :To observe scattering of light we set up an experimental arrangemernt shown here. S is a source of white light situated at the principal FOCUS of a convex lens L so that after refraction through `L_(1)` the light beam becomes a parallel beam of light. This light beam passes through a transparent glass tank 7 containing clear water. Emergent beam of light passes through a CIRCULAR hole Cmade in a cardboard sheet. A convex lens `L_(2)` forms a sharp image of the circular hole on a screen MN. Now dissolve about 200g of sodium thiosulphate (COMMONLY known as hypo) in about 2 litre of clean water taken in the tank T. Add 1 -2 mL of concentrated sulphuric acid to the water. We observe fine microscopic sulphur particles precipitating in about 2-3 minutes. As the colloidal sulphur particles begin to form, we observe the blue light from the THREE sides of the glass tank. It is due to scattering of blue light of short wavelengths by colloidal sulphur particles. Consequently, the TRANSMITTED light through the tank, which is finally focussed on screen MN, at first appears of orange-red colour and then of bright crimson red colour.