Principle

Optically active substances such as sugar solution and quartz
rotate the polarization plane of the Iight passing through them.
The optical activity is brought about by the form of the sugar
molecules in the sugar solution, or by the grid structure of the
quartz.
The angle a, by which the polarization plane of Iight is rotated in
a sugar solution, depends on the wavelength 7 of the light, the
concentration c of the solution and on the Iayer thickness d (path
travelled by the light in the solution).

This phenomenon is called rotational dispersion and we use it,
for instance, to determine the concentration of optically active
substances in solutions. The device used to determine in particular
the concentration of sugar solutions is known as the saccharimeter.
There are dextrorotatory (right-handed) and laevo-rotatory
(left-handed) optically active substances. In this experiment the
students should become familiar with the phenomenon of rotational
dispersion, its dependence on c and d, and the basic design of a
saccharimeter.


Benefits


Multifunctional light box - All-in-one: Can be used for geometric optics on the table, colour mixing and on an optical bench

Extension with others sets at anytime, no additional light sources needed, recognition value for students



Tasks


Set up a mode) of a saccharimeter and investigate what happens
to a sugar solution when polarized Iight of various wavelengths
passes through it.

Find out also, whether and to what extent the observed
phenomenon is dependent on the layerthickness and concentration of
the sugar solution.