2014-10-28T05:28:47+05:30

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Fleming's left hand rule is for indicating the direction of force F or movement of a current carrying conductor in the presence of a magnetic field.  This is applicable in motors.  There the direction of rotation of rotor is known by this rule.

Let the thumb, forefinger and the middle finger of the left hand be stretched in three perpendicular directions.  Let thumb point upwards. Let forefinger point towards in front (ahead) of you. Let the middle finger be perpendicular to the palm pointing towards the right of yours.

Let the middle finger point in the direction of the B = magnetic field (created by an electric conductor).  Let the middle finger point in the direction of current I in another conductor. Then the force F on the conductor due to B will be in the direction of the thumb.

2014-10-28T18:44:00+05:30
The direction of motion, field and current can be illustrated through a simple rule called Flemming's Left-Hand Rule. According to this rule, stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular. If the first finger points in the direction of magnetic field and second in the direction of current, then the thumb will point in the direction of motion.
Devices that use current-carrying conductors and magnetic fields include electric motor, electric generator, loudspeakers, microphones and measuring instruments.