1) A sinusoidal current-carrying stator coil produces a fundamental mmf wave:

Which pulsates with time and is equal to two rotating mmf waves rotating in the same direction and having the same peak strength of the fundamental mmf wave.
Which has constant amplitude (independent of time) and is equal two rotating mmf waves rotating in the same direction and having the same peak strength of the fundamental mmf wave.

2) The 2-phase windings of stator carrying 2-phase balanced current produces a rotating field

3) The direction of rotating field of a 2-phase synchronous motor can be reversed by changing the phase sequence connection of the 2-phase ac supply

4) The speed of a rotating magnetic field can be changed by adjusting the _________ of 2-phase currents

direction