Absorption and Scattering of Light

absorption and scattering of light the intensity of the light source can be

measured using a photometer bringing a transparent material into the optical path the intensity is only decreased by reflections in the surface the the material can be described by its refraction index if the intensity is decreased 1 needs another matter constant the extinction coefficient this coefficient is

composed of absorption and scattering and describes the decrease of intensity inside a medium the and absorption the

light entering the medium is converted into other types of energy mostly heat the to examine this phenomenon we use this set up

the light of a halogen lamp thank you is bundled violence and collimated by an iris the bundled ray of light passes through a beaker glass and the intensity of the light is measured with a photometer Hey the measuring device shows the

intensity in relax the potassium manganate solution in this

container goes through this tube which can be closed by a clip and into

this beaker dust the light has to pass through a layer of increasing thickness the particles in the solution are

so small that practically no scattering workers during the

experimental procedure 1 sees

the slowly filling beaker the photometer and a diagram that shows the intensity of the light a gains the depths of the absorber but

the exponential decrease is clearly visible but a fitting graph gives the absorption coefficient of the solution this is described in

general by landed all of absorption at scattering and the light

is not converted to other types of energy but the re-emitted in all directions an analogous set

up this time with a water-filled because it is used to examine scattering the thank

no light leaving the beaker can be seen because the water as well as the glass are passed unhindered but if milk is poured into the water and mixture with small particles is produced and the light is scattered now the dependence

of scattering from the wavelength is examined 1 sees clearly that

the red light with a longer wavelength is scatter at less than the blue light with a shorter wavelength 1 only very little intensity from the red light is lost only 10 per cent of the blue lights are original intensity or reaches the detector

examining this with different wavelengths 1 sees that the scattering decreases with the increasing wavelength cutting the wavelength in 4th power the correlation is obviously linear

thus the scattering is inversely proportional to the 4th power of the wavelength m proportional to the 4th power of the frequency using

light of only 1 wavelength the decrease of intensity can be described as analogous to the absorption according to Lambert's law the scattering coefficient is the product of the scattering cross section that describes the effective area of each particle in which the light is scattered completely and the number density of scattering particles per volume in a medium where absorption and scattering curve the extinction coefficient is the sum of both constants