when you say the the capacitor is used to smooth ... QUOTE]
In a Rectified AC to DC power supply, a capacitor of appropriate value, is employed to reduce the " AC Ripple " element in the rectified DC.
Ripple is present as noise in the DC voltage downstream from the rectifier, even with a full-wave bridge.
A filter circuit. It can either be configured as a capacitor, or choke-input
Are you sure of that? In common usage, does the "alternating" term just mean fluctuating in amplitude instead of direction? I'm not being snarky - I'm really wondering about the definitions.The AC signal does not have to reverse direction for it be designated the term AC.
That doesn't apply to current flow though. Current is not arbitrary, like voltage. And the term is alternating current, not alternating voltage, which might be more accurate.Since all voltages are relative, any signal that is changing periodically will be alternating in sign with respect to some voltage (like the RMS voltage for instance).