The neutral and my understanding.

[FionaZuppa]

This whole area of science is as yet to be well understood. The idea of a required return path is a half baked idea IMHO. EM radiation does NOT require a return path.

but this is transmission of energy. to extract that energy in the electrical form you will need a closed loop, what the "loop" actually is may vary. a FM antenna forms a "tuned closed loop", etc.

 

[winnie]

EM radiation doesn't require a return path, but most electricians work in the near field where Kirchoff's laws apply.

Kirchoff's laws describe the requirement for a closed circuit and how voltages add up in a circuit. They are not good approximations once the size of the system is a large fraction of a wavelength. At 60Hz you need a pretty large circuit for Kirchoff's laws to fail you.

-Jon

 

[GoldDigger]

EM radiation doesn't require a return path, but most electricians work in the near field where Kirchoff's laws apply.

Kirchoff's laws describe the requirement for a closed circuit and how voltages add up in a circuit. They are not good approximations once the size of the system is a large fraction of a wavelength. At 60Hz you need a pretty large circuit for Kirchoff's laws to fail you.

-Jon

Even when a system is multiple wavelengths in size, Kirchoff's laws apply quite accurately. The problem is that you can no longer approximate simple elements like wires as having a single lumped impedance but instead have to deal with the distributed resistance and reactance values, treating the element as a transmission line with a characteristic impedance and loss coefficient.
When frequencies are high enough you also need to look at the radiation resistance of an element, dropping voltage in a resistive way by virtue of radiating energy in electromagnetic waves rather than just heating.

But as long as you do not make the simplifying assumptions about circuit elements themselves which work well at DC and low frequencies, Kirchoff's laws still apply just fine.

 

[winnie]

Thanks for the correction; I was in fact saying something similar in a different forum in a discussion of antennas, so I really should have known better

-Jon