2015 BFY II Abstract Detail Page
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| Abstract Title: |
Using a Tube of Water to Screen Electric Fields: An Experimental Investigation of the Transition from Conductive to Dielectric Screening |
| Abstract: |
A common and convenient way to exclude electric fields from a region of space is to use a conducting enclosure or Faraday cage. However, it is also possible to attenuate external electric fields using dielectric enclosures. In the case of a dielectric tube that also has a non-negligible conductivity, the frequency response of the tube's shielding effectiveness is that of a high-pass filter with the screening being dominated by the conductivity at low frequencies and by the dielectric properties at high frequencies. An experiment that investigates the transition from conductive to dielectric screening of electric fields by a tube of water has been designed for senior physics undergraduates. A parallel-plate capacitor is used to generate a uniform electric field. Two concentric acrylic tubes pass perpendicularly through the electric field generated between the capacitor plates. The region between the concentric tubes can be filled with air or another fluid (water in this experiment). An electrode, suspended within the inner acrylic tube, is used to sense the electric potential at its location. The sensor is designed so that it can be rotated to measure the potential at a second symmetric position. From the difference in the two potentials, the frequency dependence of the magnitude and phase of the electric field can be determined. With deionized water between the tubes, the frequency dependence of the magnitude and phase of the interior electric field was measured from 100 Hz to 300 kHz. The expected high-pass filter frequency response was observed and fits to the data yielded an experimental value for the ratio of the water's conductivity to its dielectric constant. |
| Abstract Type: |
Poster
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Author/Organizer Information |
| Primary Contact: |
Jake Bobowski
University of British Columbia, Okanagan Campus
3333 University Way
Kelowna, British Columbia, Non U.S. V1V 1V7
Phone: 250-807-9506
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Co-Author(s)
and Co-Presenter(s) |
Jaklyn De Vos
University of British Columbia, Okanagan Campus
3333 University Way
Kelowna, British Columbia
V1V 1V7
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