Simple and inexpensive classroom demonstrations of nuclear magnetic resonance and magnetic resonance imaging
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Joel A. Olson [1] ; Karen J. Nordell [1] ; Marla A. Chesnik [1] ; Clark R. Landis [1] ; Arthur B. Ellis [1] ; M. S. Rzchowski [1] ; George C. Lisensky [2] ; S. Michael Condren [3] ; James W. Long [4]
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[1] University of Wisconsin–Madison
University of Wisconsin–Madison
City of Madison, Estados Unidos
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[2] Beloit College
Beloit College
City of Beloit, Estados Unidos
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[3] Christian Brothers University
Christian Brothers University
Estados Unidos
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[4] Department of Chemistry, University of Oregon
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 77, Nº 7 (July), 2000, págs. 882-882
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
Several demonstrations of resonance phenomena associated with nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are described. The demonstrations comprise common orienteering compasses, whose needles represent magnetic dipoles, along with three collinear permanent magnets and a magnetic stir plate or pulseable electromagnets. The trio of permanent magnets provides a laterally uniform magnetic field, whose strength decreases with distance from the magnets. Resonance can be observed by adjusting the frequency of the magnetic stirrer to match the resonant frequency of the compass needle, which is shown to depend on magnetic field strength, that is, the needle's position relative to the permanent magnets. Another demonstration involves pulsing electromagnets that apply a perpendicular magnetic field that causes the compass needles to oscillate. The effects of shielding, spin-spin coupling, magnetogyric ratio, and free induction decay can also be demonstrated. By moving the trio of permanent magnets relative to the compasses, the MRI experiment can be mimicked. Complete instructions for the construction of the demonstrations, which can be used on an overhead projector, are included.
