In the left hand rule for magnetic fields, what does the thumb represent?

In the context of the left-hand rule for magnetic fields, the thumb represents the direction of the current flow. This rule is a mnemonic used for visualizing the interaction between current, magnetic fields, and force in electric motors. When you hold out your left hand with your thumb extended and your fingers pointing in the direction of the magnetic field lines (from North to South), the thumb points in the direction in which the current is flowing through the conductor.

This association is crucial for understanding how electromagnetic devices operate, particularly in determining the relationship and directionality between these physical quantities.