Why does an AC motor rotate in one direction if the current alternates?

[Leyden]

does the magnetic field created by AC alternate? reverse poles? if so why does a motor rotate the same way every time? does it alternate in three phase as well?

thanks, if you want to direct me to literature i would appreciate that, what i have in my motors book talks about the hand rule for determining magnetic field based on current flow but the current is alternating? so why does the motor rotate the same direction every time? nothing explains it very well for me on YouTube either

 

[anorlunda]

Yes it does alternate. But sinusoidal alternation also looks like a rotating magnetic field.

This is a case where pictures work better than words. There are a number of videos on Youtube that illustrate the alternating fields. Here's one.

 

[Leyden]

awesome, thanks for the video definitely helps me out, although i still don't fully understand. so i will watch it a few more times and keep researching

thanks a bunch