Fleming’s Left-Hand Rule
Fleming’s left-hand rule gives the direction of force on a current-carrying conductor placed in a magnetic field: thumb = force, forefinger = field, middle finger = current.
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Motor rule
When a current-carrying conductor is placed in a magnetic field, it experiences a force. Fleming’s left-hand rule helps remember the direction: stretch your left hand so that the forefinger, middle finger, and thumb are mutually perpendicular. Forefinger points in the direction of magnetic field (B), middle finger in the direction of current (I), and thumb then gives the direction of force (F) on the conductor.
Magnitude of force
If the conductor of length L carries current I in a magnetic field of strength B, and the conductor is perpendicular to the field, the magnitude of the force is F = BIL. If the angle between the field and the conductor is θ, then F = BIL sin θ.
Why is Fleming’s left-hand rule often called the motor rule?