The discussion revolves around the emission of electromagnetic radiation by a point charge that is oscillating harmonically. Participants explore whether such a charge emits radiation, how its field changes over time, and the concepts of near and far fields in relation to electromagnetic radiation.
Participants generally agree that a slowly oscillating charge emits radiation, albeit at a frequency that may be difficult to detect. However, the discussion on the significance of near and far fields remains unresolved, with differing levels of understanding and clarity among participants.
The discussion includes references to specific mathematical formulations (Lienard-Wiechert potentials and field terms) that may require further elaboration for full comprehension. There is also an acknowledgment of practical limitations in detecting low-frequency radiation.
This discussion may be of interest to those studying electromagnetic theory, particularly in the context of radiation from oscillating charges, as well as those seeking clarification on the concepts of near and far fields.
The field from an arbitrarily moving point charge is given by the Lienard Wiechert potentials.TheWiseFool said:How does its field change with time.
If you look at the Lienard Wiechert formulas (the fields, not the potentials) you will see that there are a couple of terms one term is proportional to ##r^{-1}## and one proportional to ##r^{-2}##. The former is the far field and the latter is the near field. More generally, any field term that falls off faster than ##r^{-1}## is considered part of the near field.TheWiseFool said:I have not yet seen a clear, explanation of these terms and their significance. Would anyone like to try