Why is it crucial for electric motor coils to be wound in one direction?

[XxsithlordxX]

Homework Statement

Why must the coil in an electric motor kit be wound in only one direction?
Why must the current change direction every 180 degrees in the motor?

Homework Equations

No relevant equations. Just a simple answer.

The Attempt at a Solution

NI-Prentice Hall DC Motor Theory states that The armature (rotor) of a DC motor has coils of wire wrapped around its core. The ends of each coil are terminated at commutator segments located on the left end of the shaft. The brushes make contact on the commutator to provide current for the armature.

 

[Simon Bridge]

NI-Prentice Hall DC Motor Theory states that The armature (rotor) of a DC motor has coils of wire wrapped around its core. The ends of each coil are terminated at commutator segments located on the left end of the shaft. The brushes make contact on the commutator to provide current for the armature.

So far so good ... but how does that mean the coils all have to be wound the same way?

If you made the coil with, say, 20 turns clockwise and another 20 anticlockwise - how would that affect it's performance compared with 40 all the same way?

 

[CWatters]

Perhaps think about why a motor rotates in the direction it does.

 

[Simon Bridge]

@XxsithlordxX: how did you get on?