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#### macnab

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Hi guys, I'm studying electrical ac theory. My question is in regards to inductance and resistance. An inductor has a effective resistance of 4 ohms and a inductive reactance of 19.6. Total Z=20. Now in doing calculations for power etc the resistance is considered to be in series with the coil. At 60hz 120v the pf is 0.2 lagging and a phase angle of 78.5 degrees, thus the current is lagging by that amount. Now when using trigonometry the current in the pure resistance part of the series circuit is considered to be in phase with the voltage. However there iare not two currents in a series circuit, i.e. one in phase and the other lagging, there can be only one current, this being the lagging current. So my question is how can the trigonometry state there is a current that is in phase with the voltage?

I did a plot of the vars supplied to the coil and vars returned to the supply, these are not equal, the vars supplied is higher. My point is that the true power in watts is the difference between the vars supplied and vars returned, not due to current that is "in phase" with the voltage - does this make sense or am I missing something.

Any thoughts really appreciated.

Mac.

I did a plot of the vars supplied to the coil and vars returned to the supply, these are not equal, the vars supplied is higher. My point is that the true power in watts is the difference between the vars supplied and vars returned, not due to current that is "in phase" with the voltage - does this make sense or am I missing something.

Any thoughts really appreciated.

Mac.