Earlier, I wrote:
AI4QJ wrote:
In an inductor, current lags voltage. If you connect a resitor and a
coil in parallel and apply AC, EE101 tells you that, although the
phase of the voltage across them stays the same, the current is
"delayed" by the phase angle in the inductor when compared to current
resistor.

No, it isn't - the phase of the current around the circuit has to
stay the same. Think of the simplest possible circuit: an AC voltage
source (of zero internal impedance) with one terminal wired to R,
lumped L in series, and directly back to the other terminal of the AC
source. If the phase of the current were delayed through L as you
suggest, there would then be a difference in phase between the two
terminals of the AC source... which is obviously not true.

It's the magnitude and phase of the voltage that varies at different
points around the circuit; but the magnitude and phase of the current
has to remain the same all the way around the loop. In more formal
terms, Kirchhoff's current law applies all around the circuit; and it
most certainly applies between the two terminals of a lumped inductance.

My apologies to AI4QJ. He was talking about a parallel R-L circuit, and
my reply was about a series R-L circuit. Each of our statements was
correct in its own context.

Thanks to Tom B for pointing this out.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek