When a current carrying conductor is placed in the magnetic field, conductor experiences a force due to the magnetic field. While when a conductor moved in a magnetic field, an emf is induced across the conductor according to Faraday’s law of electromagnetic induction.
J. A. Fleming introduced two important rules to determine the direction of motion or force in case of motor and the direction of induced current in case of generator. These rules are called as Fleming’s left hand rule (used for motors) and Fleming’s right hand rule (used for generators) respectively.

Fleming’s Left Hand Rule

The conductor experiences a force whenever a current carrying conductor is placed in a magnetic field. The direction of force is perpendicular to both the magnetic field and the direction of current. 
Fleming’s left hand rule says that if the thumb, fore-finger and middle finger of the left hand are stretched and perpendicular to each other as shown in the figure below. Then the fore finger will represents the magnetic field direction, middle finger represents the current direction, then the thumb represents the force direction. Fleming’s left hand rule is used in motors for finding the direction of rotation of motor.
How To Remember Fleming’s Left Hand Rule?
Trick 1: Assume the thumb with thrust, fore finger with magnetic field and center-finger with current i.e. First letters will make you remember the fingers with their directions.
1. Thumb represents the direction of Thrust on the conductor (force on the conductor).
2. Fore finger represents the magnetic Field direction.
3. Center finger (middle finger) represents the Current direction.
Trick 2: Assume the Fleming’s left-hand rule with the short form FBI.
where, F represents Force, B represents magnetic flux density and I represents Current. Attribute these letters F to the thumb, B to the first finger and I to the middle finger. 

Fleming’s Right Hand Rule

When a conductor is moved in an electromagnetic field, an emf is induced across the conductor according to Faraday’s law of electromagnetic induction. If this conductor is given a closed path, then an induced emf causes a current to flow in the conductor. 
Fleming’s right hand rule says that if the thumb, fore-finger and middle finger of the right hand are stretched and perpendicular to each other as shown in the figure below. Then the thumb represents the conductor movement direction, fore-finger represents the magnetic field direction, then the middle finger represents the induced current direction. Fleming’s right hand rule is applicable for electrical generators. 
How To Remember Fleming’s Right Hand Rule?
As we have given tricks to remember Fleming’s Left Hand Rule. Similarly these tricks can be applied to Fleming’s Right Hand Rule.  
Fleming’s Left Hand Rule And Right Hand Rule
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