Are Moving Electric Fields Equivalent to Magnetic Fields?

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Electric and magnetic fields are interrelated, as established in Einstein's 1905 paper "On The Electrodynamics Of Moving Bodies." In static conditions, such as in a magnetostatic scenario with a current-carrying loop, a magnetic field exists without an electric field in a stationary frame. Conversely, in an electrostatic condition with static charges, an electric field is present without a magnetic field in the rest frame. When observed from a moving reference frame, both electric and magnetic fields emerge due to relativistic effects. Ultimately, neither field is more fundamental than the other, highlighting their mutual coexistence in different reference frames.
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Moving electric field = magnetic field?
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how come you ask?
 
https://www.physicsforums.com/showthread.php?t=175438&highlight=cabraham

This issue was thoroughly addressed in the above thread. Read through the entire thread and then we can discuss any questions you have. The crux of my contribution was Einstein's 1905 paper "On The Electrodynamics Of Moving Bodies".

The long and short of it, according to Albert Einstein himself, was that the electric and magnetic fields mutually coexist, and neither is more "fundamental" than the other. The point that some fail to acknowledge is that there are 2 "static" conditions, namely electrostatic, and magnetostatic.

A magnetostatic condition exists with a current carrying loop of steady (dc) value. A magnetic field surounds the wire, but there is zero electric field. This is with respect to the stationary reference frame. To an observer in a reference frame at motion wrt the rest frame (steady velocity, no acceleration), there will be an electric field as well as magnetic.

An electrostatic condition exists when static charges are separated, such as a capacitor charged to a steady (dc) voltage. In the rest frame, an electric field exists, with zero magnetic field. In a moving reference frame, again constant velocity w/ no accelaration, both electric and magnetic fields exist.

According to Einstein, neither the electric nor the magnetic field is the "seat". The term "seat" denoted the "root" or "basis" quantity. In conclusion, electric and magnetic fields are relativistically related.
 
Hello! Let's say I have a cavity resonant at 10 GHz with a Q factor of 1000. Given the Lorentzian shape of the cavity, I can also drive the cavity at, say 100 MHz. Of course the response will be very very weak, but non-zero given that the Loretzian shape never really reaches zero. I am trying to understand how are the magnetic and electric field distributions of the field at 100 MHz relative to the ones at 10 GHz? In particular, if inside the cavity I have some structure, such as 2 plates...

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