| Electronics > Beginners |
| Displacement current, where is it in electronics? |
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| lordvader88:
Although I have done some stuff with the differential form of Maxwell's eq's and with Clifford algebra, I never did enough to understand what the displacement current is (I just did it for fun on my own, not in class with problems/applications/tests) So where/when does it show up in EE courses, dealing with resistors, capacitors, inductors, and semi-conductors? I do have utube, but I'm asking anyways |
| Wimberleytech:
I watched the video. It should answer you question very well. Displacement current is the current that charges a capacitor. It shows up in EE everywhere capacitors are discussed (which includes semiconductors). It may be called "charging current" instead of "displacement current." |
| rfeecs:
--- Quote from: lordvader88 on July 19, 2018, 04:02:35 pm --- So where/when does it show up in EE courses, dealing with resistors, capacitors, inductors, and semi-conductors? --- End quote --- Pretty much nowhere. Although sometimes it is mentioned in dealing with capacitors, it is not needed to understand or describe how a capacitor works. It might be mentioned in a discussion of how to apply Kirchhoff's law to one plate of a capacitor or something obscure like that. Where it is mentioned is when you have propagating electromagnetic fields: in antennas, transmission lines, waveguides. Maxwell added a term to Ampere's law: Ampere's law says that a current produces a magnetic field. The term Maxwell added is the displacement current. It says that a changing electric field also acts like a current and also produces a magnetic field. Now, Faraday's law says that a changing magnetic field produces an electric field; the displacement current addition says that a changing electric field produces a magnetic field. So the two coupled fields can create an electromagnetic wave that can propagate through space. This can only be explained by adding the displacement current to Ampere's law. |
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