Current through a capacitor in AC Circuits I'm a little confused on the equation for the instantaneous current through a capacitor in AC circuits.
My textbook has it as:
$$i_C = \omega CV \ cos(\omega t + \pi/2) = -\omega CV \ sin(\omega t)$$
where $\omega$ = angular frequency, $C$ is the capacitance, and $V$ is the voltage across the capacitor.
I'm also seeing it in some places online (and in the problem "hints" for my homework) without the the "+ $\pi/2$" part, and I'm not sure why. Any ideas?
To add to my confusion, the equation for the current through the inductor in the problem "hints", is consistent with the textbook:
$$i_L = (V/\omega L) \ cos(\omega t - \pi/2) = (V/\omega L) \ sin(\omega t)$$
The problem in question relates to this circuit:

 A: The pi/2 term comes about when converting angular measure from degree units to radian units, where 2(pi) radians equals 360 degrees.
BTW here is a simple way to visualize current flow through a capacitor:
Imagine two flat metal plates facing each other with nothing but air between them. Each plate is connected to a wire into which we can squirt extra electrons or suck some out. The wires and plates are electrically neutral which means there are equal numbers of electrons on both plates and wires.
Now we suddenly squirt some extra electrons into one of the plates and those extra electrons then flow into the plate and "face off" against the electrons sitting on the other plate, across the gap.
There are now more electrons on one plate than there are on the other and in response, some of the electrons on the other plate get repelled off of it and flow out through the wire attached to it, forming a brief burst of current that dies off when the potentials on both plates becomes equal and opposite.
Hence, for a brief instant, there was a squirt of current that entered one plate and left through the other even though there was no physical connection between the two plates. Since AC currents are all about sudden change, AC currents can flow through capacitors whereas DC currents cannot.
