Today we will discuss about,

**Who invented Fleming left hand and right hand rule?****Fleming left hand rule****Applications of Fleming left hand rule****Fleming right hand rule****Application of Fleming right hand rule****Difference between Fleming left hand and right hand rule**

So let's go to learn.

## Who invented Fleming left hand and right hand rule?

In the 19th century, John abrose Fleming invent two rules known as Fleming left hand rule and Fleming right hand rule to find out the direction of force in a current carrying conductor placed in a magnetic field or the direction of induced current in the conductor rotating in the magnetic field respectively.

## Fleming left hand rule: -

- As discussed above Fleming left hand rule is used to find out the direction of induced force in a current carrying conductor placed in a magnetic field.
- This rule is only used to find out the direction of force and cannot be used to find out the magnitude of the force.
- According to Fleming left hand rule, if we stretch our thumb, forefinger, and middle finger in such a way that they all align at 90° to each other (perpendicular to each other) then the thumb will show the direction of induced force, forefinger will show the direction of the magnetic field and the middle finger will show the direction of current flowing through the conductor.
- This rule is used to find out the direction of current, magnetic field, or force if two parameters are known of them.

*How to find the magnitude of the force acting on the current carrying conductor placed in the magnetic field?*

As we can easily find the direction of force from the Fleming left hand rule (if direction of current and magnetic field known).

So to find the magnitude of this force we can use the formula as given below: -

**F = BiL Newton's**

Where,

F = magnitude of force

B = magnetic field

i = current flowing through the conductor

L = length of the conductor.

## Applications of Fleming left hand rule: -

This rule is used to find out the direction of force in the electric motors used in fans, mixture, printers, etc.

*How to remember Fleming left hand rule: -*

To remember easily the Fleming left hand rule relate the thumb with force F, forefinger with the magnetic field B, and middle finger with current I.

*FBI trick: -*

**F**= force (thumb)

**B**= magnetic field (forefinger)

**I**= current. (Middle finger),

## Fleming right hand rule: -

- According to Faraday's law of electromagnetic induction whenever a conductor rotates in a magnetic field an emf will produce in it and if the circuit is close then a current will also flow through it.
- So to find out the direction of this induced current in the conductor we use the Fleming right hand rule.
- As we have already discussed above the Fleming right hand rule is used to find out the direction of induced current in a conductor rotating in a magnetic field.
- This rule is also used to find out the direction only and cannot be used to find out the magnitude of the induced current.
- According to Fleming right hand rule, if we stretch our right hand thumb, forefinger, and middle finger in such a way that they align 90° to each other (means perpendicular to each other) then the thumb will show the direction of applied force, forefinger will show the direction of the magnetic field and middle finger will show the direction of induced current in the conductor.

## Application of Fleming right hand rule: -

The Fleming right hand rule is used to find out the direction of current induced in the electric generators.

*How to remember Fleming left hand rule: -*

To remember easily the Fleming right hand rule relates again the thumb with force F, forefinger with the magnetic field B, and middle finger with current I.

Use again FBI trick.

#### So *what is the difference between Fleming left hand rule and Fleming right hand rule?*

Fleming left hand rule | Fleming right hand rule |

1. This rule is given by John abrose Fleming in 19th century | This rule is also given by John abrose Fleming in 19th century |

2. The Fleming left hand rule is used in electric motors. | The Fleming right hand rule is used in electric generators. |

3. In the Fleming left hand rule, the thumb shows the direction of induced force. | In the Fleming right hand rule, the thumb shows the direction of applied force. |

4. In the Fleming left hand rule, the forefinger shows the direction of the magnetic field. | In the Fleming right hand rule, the thumb shows the direction of the magnetic field. |

5. In the Fleming left hand rule, the middle finger shows the direction of current flow through the conductor. | In the Fleming left hand rule, the middle finger shows the direction of induced current. |

## Conclusion: -

The john abrose Fleming invented two rules, i.e. Fleming left hand and Fleming right hand rule which are used to find out the direction of induced force in electric motors and direction of induced current in electric generators respectively.

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