2015 BFY II Abstract Detail Page
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||W21 - Brownian Motion: Measuring Avogadro’s Constant for $70
||Brownian motion played a pivotal role in the development of modern physics. One of the four papers in Einstein's 1905 annus mirabilis explained Brownian motion using atomic theory. Up until this publication, there were still prominent physicists who believed that atoms were a convenient fiction, but not real objects; Einstein's paper provided the convincing evidence for their existence.
Through measurements of Brownian motion, students can measure a fundamental constant, Avogadro's number, from which they can determine the size of atoms.1 Additionally, they are introduced to a currently active research area--in the past 12 months, there have been 90 manuscripts submitted to cond-mat on Brownian motion.
These inexpensive measurements are made possible by using microscopes from the consumer market, solutions of polystyrene spheres of uniform size, and the image processing software ImageJ available free from the NIH. During this session, participants will learn how to set up the experiments and analyze the data to yield accurate measurements (within a few percent) of Avogadro's number and Boltzmann's constant.
Participants should bring their own laptops and will receive instructions in advance for downloading the ImageJ software.
1. "Einstein, Perrin, and the reality of atoms: 1905 revisited," Ronald Newburgh, Joseph Peidle, Wolfgang Rueckner, American Journal of Physics 74 6, June 2006.