Silly question about voltage and current

[dieter]

What I was talking about was: in AC a cap as well as a coil will bring the current out of phase. There is a moment in the AC cycle where there is full current at the cap, but zero voltage, and there's a moment where there's full voltage at the coil, but zero current. If you would use a mechanical or electronic switch to tap that very moment only and then "mix" the currentless voltage with the voltageless current, would anything happen?


But I do assume, even if the current is out of phase, energy is consumed nonetheless.

[TinselKoala]

What I was talking about was: in AC a cap as well as a coil will bring the current out of phase. There is a moment in the AC cycle where there is full current at the cap, but zero voltage, and there's a moment where there's full voltage at the coil, but zero current. If you would use a mechanical or electronic switch to tap that very moment only and then "mix" the currentless voltage with the voltageless current, would anything happen?

Uh.... no. Or maybe yes. You see, when you set up impossible initial conditions, it's impossible to predict outcomes. Sort of like dividing by zero.

But I do assume, even if the current is out of phase, energy is consumed nonetheless.

Not necessarily. As we covered before, AC power fed to reactive circuit components will exhibit phase shift between voltage and current. This results in the "power" being partitioned into "real" power and "reactive" power. The reactive power isn't dissipated.

From Wiki:

In the diagram, P is the real power, Q is the reactive power (in this case positive), S is the complex power and the length of S is the apparent power. Reactive power does not do any work, so it is represented as the imaginary axis of the vector diagram. Real power does do work, so it is the real axis.
The unit for all forms of power is the watt (symbol: W), but this unit is generally reserved for real power. Apparent power is conventionally expressed in volt-amperes (VA) since it is the product of rms voltage and rms current. The unit for reactive power is expressed as var, which stands for volt-ampere reactive. Since reactive power transfers no net energy to the load, it is sometimes called "wattless" power. It does, however, serve an important function in electrical grids and its lack has been cited as a significant factor in the Northeast Blackout of 2003.^[2]
Understanding the relationship among these three quantities lies at the heart of understanding power engineering. The mathematical relationship among them can be represented by vectors or expressed using complex numbers, S = P + jQ (where j is the imaginary unit).

http://en.wikipedia.org/wiki/AC_power

[Dave45]

So if voltage is pressure and current is flow tell me how there can be a phase shift between the two,

[MarkE]

So if voltage is pressure and current is flow tell me how there can be a phase shift between the two,

That's easy, set up a channel with an accumulator attached.  If you increase the pressure in the channel, more water will store in the accumulator, and the flow downstream will not increase in lock step with the pressure increase.  Likewise, when you decrease the upstream pressure, the accumulator will release water and the flow downstream will not decrease in lock step with the pressure decrease.  This is why municipal water systems have water tower accumulators.

[Dave45]

Ok sounds plausible for water, tell me if alternating current is just current alternating through a conductor then why does this circuit build a negative ion cloud on one end and a positive ion cloud on the other.
If negative current were the only energy moving in the coil wouldnt we have a negative ion cloud only on one end of the circuit.