With the proliferation of electronic systems in every aspect of our daily lives, there inevitably comes the problem of compatibility. Listening to the news on AM radio while using an electric razor shouldn't be a problem, thanks to EMC design practices on the part of the razor manufacturer. The three constituents of EMC are [unwarranted] Emissions, [inappropriate] Susceptibility, and the [unintended] Path between them. The electric razor's motor brushes arcing is a case of unwarranted Emissions; and the AM radio's picking up the noise through the Path(s) (power line, and/or through the air), is the unnecessary Susceptibility. Path consists of Radiated and Conducted energy. 1. Radiated (electromagnetic field) 2. Inductively coupled (magnetic field) 3. Capacitively coupled (electric field) 4. Conducted (electric current)
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![](http://www.williamson-labs.com/images/magnetic-coupling.jpg) | ![](http://www.williamson-labs.com/images/magnetic-coupling-tight.jpg) | Inductively coupled (magnetic field) | Inductively coupled, (magnetic field) | | | ![](http://www.williamson-labs.com/images/capacitive-coupling_nshield.gif) | ![](http://www.williamson-labs.com/images/capacitive-coupling_shield.gif) | Capacitively coupled (electric field) | Capacitively coupled W/Shield (electric field) | | | ![](http://www.williamson-labs.com/images/microstrip-hiz.gif) | ![](http://www.williamson-labs.com/images/microstrip-loz.gif) | Microstrip Transmission Line Characteristic Impedance affected by ground plane proximity: Z = High | Microstrip Transmission Line Characteristic Impedance affected by ground plane proximity: Z = Low |
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