I want to know the answer to the following question:
What non-motor device demonstrates why a commutator is needed?
All the background I'm provided with is that "The commutator switches power to the coils as the rotor turns, keeping the magnetic poles of the rotor from ever fully aligning with the magnetic poles of the stator field, so that the rotor never stops (like a compass needle does), but rather keeps rotating as long as power is applied.". Is that enough to answer the question?