2015 BFY II Abstract Detail Page
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||W02 - Nanoparticle Scattering of Polarized Light
||This experiment allows students to explore electric dipole radiation in the opticalfrequency domain. Here, electric dipoles are induced in nanoparticles suspended in water by the electric field of a linearly polarized HeNe laser beam and the resulting angular distribution of optical radiation in the plane normal to the incident beam is compared to the expected sin2? distribution.
This experiment is highly flexible, with implementations that span a range of simplicity and cost. Details of the construction of the experiment and analysis of the data will be provided. The polarization, particle size and concentration dependence of the angular distribution, and the radial dependence of the irradiance will be discussed. The apparatus will be available for use and typical results will be presented. Finally, the ways in which this experiment can be used to meet many of the learning outcomes described in the AAPT Recommendations for the Undergraduate Physics Laboratory Curriculum will be discussed.
For graduate students, the experiment can be extended to the study of magnetic dipole (and/or electric quadrupole) radiation by mounting a polarizer in front of the detector. The experiment can help elucidate the polarization and angular distribution of low order multipole radiation when teaching multipole fields. Many details are contained in Am. J. Phys. [71, 1294 (2003)] and Phys. Rev. Lett. [98, 217402 (2007)].
After doing the experiment, students understand how electric dipole radiation explains polarization by reflection (Brewster's angle), polarization by scattering, and the polarization of radiation emitted by circulating charges (as in pulsars).
Eastern Michigan University
Natthi Sharma, Eastern Michigan University