Force on a moving charge — common mistakes

Pay close attention to the direction of charge (positive or negative) when applying Fleming's Left-Hand Rule. For negative charges, remember to reverse the direction of the force you find, or use the middle finger for current/motion in the opposite direction of actual electron flow.

The magnetic force only acts if the charge is moving and has a velocity component perpendicular to the magnetic field. An electric force acts on any charge (moving or stationary) in an electric field.

When a charged particle moves perpendicularly to a uniform magnetic field, the magnetic force acts perpendicular to its velocity at all times. This continuously changing force direction provides the centripetal force required for circular motion.

Yes, the polarity of the Hall voltage (which side becomes positive or negative) directly indicates whether the charge carriers are positive (holes) or negative (electrons).