When a current-carrying conductor is placed in a magnetic field it experiences a force due to its field, and the direction of that force is determined by Fleming’s Left-Hand Rule. Similarly on the other hand, When a moving conductor is placed in a magnetic field then an EMF is induced in the conductor, and hence current flows through the conductor. Then the direction of that induced current is determined by Fleming’s Right-Hand Rule.
In both rules (Fleming left-hand rule and Fleming right-hand rule), there is a relationship between the direction of Force, Magnetic field, and Current. This relation can be determined by the Left-hand rule and the Right-hand rule.
These rules don’t determine the magnitude instead it finds only the direction of any of these three parameters (Force, Magnetic field, and Current) when the direction of the other two parameters is known.
Fleming’s left-hand rule is used to find the direction of motion of the motor. Whereas, Fleming’s right-hand rule is used to find out the direction of induced current in the generator.
As the name suggests both rules were invented by John Ambrose Fleming in the 19th century. That’s why these are known by his name as Fleming Left-hand rule and Fleming right hand rule. Sometimes in short, It is also known as simply the Left-hand rule and Right-hand rule.
Fleming’s Left-Hand Rule
It is observed that Whenever a current-carrying conductor is placed in an external magnetic field It experiences a Force (F) perpendicular to the direction of both Magnetic field (B) and Current (I). Fleming left-hand rule is used to find out the direction of force acting on current carrying conductor with the help of other two (direction of Magnetic field and Current). Hence Fleming left-hand rule is used to determine the direction of motion of motor.
Fleming left-hand rule states that: If we arrange our Thumb, Forefinger, and Middle finger of the left hand perpendicular to each other, then the Thumb points towards the direction of Force experienced by the current-carrying conductor, the Forefinger or index finger points towards the direction of the Magnetic field, and Middle finger points towards the direction of electric current.
According to Fleming left-hand rule, If Thumb, Forefinger and Middle finger of left hand are perpendicular to each other, then:
Thumb:- represents direction of Force (F)
Forefinger:- represents direction of Magnetic field (B)
Middle finger:- represents direction of Current (I)
How to Remember Fleming’s Left-Hand Rule
To remember Fleming’s left-hand rule in a simple and easy way just relate the Thumb with Thrust, Forefinger with Field, and Center Finger or middle finger with Current as explained below:
- Thumb points towards the direction of Thrust or Force (F) on the conductor.
- Forefinger points toward the direction of the Field or Magnetic field (B)
- Centre Finger or middle finger points towards the direction of the Current(I).
Fleming’s Right-Hand Rule
According to Faraday’s law of electromagnetic induction, Whenever any conductor forcefully is moved in an external magnetic field, then an EMF gets induced across the conductor. If that conductor provides a closed path then induced EMF causes to flow current in the conductor. Then relation among the direction of these three ( Force or Thrust, Magnetic field, and Current) is determined by Fleming’s right-hand rule.
So Fleming’s right-hand rule is used to find out the direction of current flowing in the moving conductor with the help of the other two (direction of Magnetic field and direction of motion or Force). Fleming’s right-hand rule is applicable to generators.
Fleming’s right-hand rule states that: If we arrange our Thumb, Forefinger, and Middle finger of right-hand perpendicular to each other, then the Thumb points towards the direction of Force (F) or motion of the conductor relative to the magnetic field, the Forefinger or index finger points towards the direction of Magnetic field (B), and Middle finger points towards the direction of electric current (I).
So we can also conclude that:
According to Fleming right-hand rule, If Thumb, Forefinger and Middle finger of right hand are perpendicular to each other, then:
Thumb:- represents direction of motion or Force (F)
Forefinger:- represents direction of Magnetic field (B)
Middle finger:- represents direction of Current (I)
How to Remember Fleming’s Right-Hand Rule
To remember Fleming’s right-hand rule in a simple and easy way just relate the Thumb with Thrust, the Forefinger with Field, and the Center finger or middle finger with Current as explained below:
- Thumb points towards the direction of the Thrust or Force (F) or motion of the conductor.
- Forefinger points toward the direction of the Field or Magnetic field (B)
- Centre finger or middle finger points towards the direction of the Current (I).
Difference between Fleming’s Left-Hand Rule and Right-Hand Rule
The main difference between Fleming left left-hand rule and Right-hand rule is: that Fleming’s left-hand rule finds out the direction of magnetic force acting on the conductor, Whereas Fleming’s Right-hand rule finds the direction of induced current in the conductor.
| Difference between left-hand rule and Right-hand rule | |
|---|---|
| Fleming Left-Hand Rule | Fleming Right-Hand Rule |
| It is applicable to Motor | It is applicable to Generator |
| Middle finger represents the direction of current | Middle finger represents the direction of the induced current |
| Purpose is to find out the direction of the magnetic force acting on the conductor | Purpose is to find out the direction of the induced current in the conductor |
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