- Fleming's left hand rule
Fleming's left hand rule (for
electric motor s) shows the direction of thethrust on a conductor carrying a current in amagnetic field .The left hand is held with the
thumb ,index finger andmiddle finger mutually atright angles . It can be recalled by remembering that "motors drive on the left, in Britain anyway."* The First finger represents the direction of the Field.
* The Second finger represents the direction of the Current (in the classical direction, from
positive tonegative ).* The Thumb represents the direction of the Thrust or resultant Motion.
There also exists
Fleming's right hand rule (forgenerators ). The appropriately-handed rule can be recalled by remembering that the letter "g" is in "right" and "generator".Both
mnemonics are named after British engineerJohn Ambrose Fleming who invented them.Other mnemonics also exist that use a
left hand rule or aright hand rule for predicting resulting motion from a pre-existing current and field.De Graaf's translation of Fleming's left-hand rule - which also uses thrust, field and current - and the right-hand rule, is the FBI rule. The FBI rule changes Thrust into F (Lorentz force), B (direction of the magnetic field) and I (current). The FBI rule is easily remembered by US citizens because of the commonly known abbreviation for the
Federal Bureau of Investigation .Right-handed variant
A right-handed variant of this rule is as follows:If the current through a wire is in the direction of the thumb of the right hand, and the direction of an external magnetic field on the wire is represented by the fingers, then the force experienced by the wire will be in the direction the palm of the right hand is facing.
ee also
*
Fleming's right hand rule for generators
*Right hand rule
*FBI mnemonics External links
* [http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/MagneticField/RightHandRule.html Overview at ac.wwu.edu (Right Hand - 'FIB')]
* [http://micro.magnet.fsu.edu/electromag/electricity/generators/index.html Diagrams at magnet.fsu.edu. See figure #9. (Left Hand - 'FBI')]
* [http://www.starprof.com/ac/physpring04/phy030804pp/sld014.htm Description at starprof.com (Right Hand - 'IBF' - palm alternative)]
* [http://www.gcse.com/energy/motor.htm Memorable mnemonics at gcse.com]
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