You folks are mostly arguing definitions at this point IMHO and I don't
want to get involved in that. However, there's something here that bugs
me whenever I think about this stuff.
Michel Jullian wrote:
Energy stored in a pure inductor is fully recoverable actually
Yes, of course, v = -L dI/dt and what goes in must come out.
But as someone mentioned, when you turn on the power an EM wave travels
out from the inductor at C, carrying energy. How's that energy get back
to the inductor again when we open the circuit? If it doesn't, then
that formula, v = -L dI/dt, must not be quite correct.
Related issue: If the inductor is part of a transformer the "other
coil" absorbs energy and that doesn't come back out (or, rather, it
comes out the "other side" of the transformer). But if we separate the
primary and the secondary coils by significant distance, the primary
doesn't know for a long time that the secondary absorbed some of the
energy -- so how does it know it shouldn't give back the full complement
of energy to the power supply during the second half of the cycle?
This is particular interesting with regard to an antenna, which seems
like it's just a transformer with a lot of distance between primary and
secondary. An antenna is basically just an ideal inductor, yet it
radiates away power that doesn't come back out at the terminals. What's
the difference between an antenna and a simple coil, _aside_ from the
fact that we "think about" an antenna as broadcast device and a coil as
an energy storage device?
Maybe the answer is obvious if you work through the math but antenna
theory is messy enough that "working through the math" is a nontrivial
exercise...
