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Changed environment from air to water doesn't alter electric field

Posted Jul 1, 2013, 4:49 p.m. EDT MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.3 3 Replies

Daniel Livingston
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Good afternoon,

I have two electrodes set apart several microns, with their voltages set to p/m 5 V, and I'm measuring the electric field norm between the two tips. I want to see what would happen to the E-field when, instead of being surrounded by air, they are submerged in water.

I have a large cube surrounding the electrodes, with its material set to air. When I take a 4 micron high, Z-axis cut line to get the electric field between the electrodes, the 1D plot is identical whether or not the cube is material set to air or to water. I've changed the electrical conductivity of water from the COMSOL default value of 5.5E-6 S/m to 0.05 S/m, but no luck: the data is still identical, the electric field unchanged.

Any ideas on what I could be doing wrong?

Thank you all,
Cheers,
Daniel
3 Replies Last Post Jul 5, 2013, 1:41 p.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Jul 1, 2013, 5:07 p.m. EDT

Daniel,

I would think that the result is correct. With the electrodes at fixed potentials the electric field should not depend on the properties of the (homogeneous) material in between.

Cheers
Edgar


--
Edgar J. Kaiser
www.emphys.com
Daniel, I would think that the result is correct. With the electrodes at fixed potentials the electric field should not depend on the properties of the (homogeneous) material in between. Cheers Edgar -- Edgar J. Kaiser http://www.emphys.com
Daniel Livingston
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Posted: 1 decade ago Jul 5, 2013, 1:25 p.m. EDT
Edgar,

Thank you for your response. Does the dielectric constant of the material in between not matter in this case, and if so, why not?

Cheers,
Daniel
Edgar, Thank you for your response. Does the dielectric constant of the material in between not matter in this case, and if so, why not? Cheers, Daniel
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Jul 5, 2013, 1:41 p.m. EDT
Daniel,

this is a matter of boundary conditions. If you kepp the potentials constant (as you do) the field will stay constant. If you keep the charge on the boundaries constant the field (and the potentials) will change.

These are very basic concepts in electrostatics and you might take some benefit from consulting a textbook. Using a tool like COMSOL you have to understand the basics otherwise you won't be able to interpret the results.

Cheers
Edgar

--
Edgar J. Kaiser
www.emphys.com
Daniel, this is a matter of boundary conditions. If you kepp the potentials constant (as you do) the field will stay constant. If you keep the charge on the boundaries constant the field (and the potentials) will change. These are very basic concepts in electrostatics and you might take some benefit from consulting a textbook. Using a tool like COMSOL you have to understand the basics otherwise you won't be able to interpret the results. Cheers Edgar -- Edgar J. Kaiser http://www.emphys.com

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