Motor Principle
Principle
A current carrying a conductor that cuts across an external magnetic field experiences a force perpendicular to both the magnetic field and the direction of current flow.
Left Hand Rule
FBI
FBI: Forces and Motion, B-field, Current.
Important
The fingers are not necessarily
Visualization
Equation
The equation for this force, as defined in the cupboard formulae is:
where
In the case above,
Note
The fingers don't HAVE to be in the FBI configuration, that's just a mnemonic. Instead, it's just the cross-product result. The middle finger is the first vector, and the index finger is the second vector. That's just the order they were crossed.
The Electric Motor
As the motor moves from 2-3, the commutator switches brushes, switching north and south of the armature.