The core ends are arranged relative to the teeth such that 1) when both coils are energized to induce poles in the teeth, at least three consecutive teeth will be magnetized with alternate polarity, and 2) when one of the coils is deenergized, the fields will be unbalanced to impose {HEAD ~ a rotational force} on {TAIL ~ the rotor} 
The core ends are arranged relative to the teeth such that 1 ) when both coils are energized to induce poles in the teeth , at least three consecutive teeth will be magnetized with alternate polarity , and 2 ) when one of the coils is deenergized , the fields will be unbalanced to impose { HEAD ~ a rotational force } on { TAIL ~ the rotor }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL