An oscillating point charge emits electromagnetic radiation, even at low frequencies, though the energy becomes undetectable below the noise level of experiments. The behavior of the charge's field over time is described by the Lienard-Wiechert potentials, which differentiate between near and far fields. The near field is characterized by terms that decay faster than r-1, while the far field is proportional to r-1. Understanding these concepts is crucial for analyzing electromagnetic radiation from moving charges.
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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