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why the current equals OA in magnet coil-model

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I have analzyzed the problem induced volatage in the moving magnet (example from the comsol website). Why the induced current uquals 0A, but voltage is induced? Moreover, why the coil diameter does not influences on the induced voltage.



1 Reply Last Post 14.02.2022, 22:25 GMT-5
Robert Koslover Certified Consultant

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Posted: 2 years ago 14.02.2022, 22:25 GMT-5
Updated: 2 years ago 14.02.2022, 22:26 GMT-5

This is the "induced_voltage_moving_magnet.mph" model, I presume? 1. It's an open-circuit coil. If you go to Magnetic Fields --> Coil 1, then Settings --> Coil Excitation, you can see it says Current and Icoil is set to 0. If you change that to Voltage and then set Vcoil equal to zero, and re-run the model, you'll find a non-zero current (but no voltage). There are other settings there too that you might want to explore. 2. In regard to the coil diameter question, the induced voltage in the open circuit model should follow from Faraday's law, and be based on the time-changing magnetic flux through the coil. Based on that, what dependence would you expect to see? As an old movie once told me (ok, I may be paraphrasing just a bit), "follow the flux."

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
This is the "induced_voltage_moving_magnet.mph" model, I presume? 1. It's an **open-circuit** coil. If you go to Magnetic Fields --> Coil 1, then Settings --> Coil Excitation, you can see it says *Current* and *Icoil* is set to 0. If you change that to *Voltage* and then set *Vcoil* equal to zero, and re-run the model, you'll find a non-zero current (but no voltage). There are other settings there too that you might want to explore. 2. In regard to the coil diameter question, the induced voltage in the open circuit model should follow from Faraday's law, and be based on the time-changing magnetic flux through the coil. Based on that, what dependence would you expect to see? As an old movie once told me (ok, I may be paraphrasing just a bit), "follow the flux."

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