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A simple, low-cost, fully automated polarimeter, which demonstrates fundamental properties of
skylight scattering and polarization for undergraduate physics students, is described. The polarimeter
includes a microprocessor-based control unit, a Sun tracker, an elevation-azimuth mount with two
degrees of freedom, and a polarization sensor unit equipped with a light-dependent resistor for
measuring light intensity. Results obtained in the principal plane of the Sun using the polarimeter on
a relatively clear day, together with the theoretically expected results for a molecular atmosphere, are
presented. A root-mean-square error comparison indicates fairly good agreement between theory and
experiment. Construction and experimentation with the polarimeter will provide students with insight
into important physical concepts involved in skylight scattering and polarization as well as improve
their instrumentation capabilities.
