# Fleming's left and right hand rule - how do they work?

• Daniel2244
In summary: The direction of force would be up when the magnetic field is towards the right and down when the magnetic field is towards the left.
Daniel2244

## Homework Statement

AC production and relationships that determine movement and current flow direction from Flaming's left hand and right hand rule.

## The Attempt at a Solution

Left hand rule for motors- right hand rule for generators
The thumb, index and midle fingers are all right angles to each other.
For left hand rule: I use FBI - thumb = direction of force, index finger = magnetic field and middle finger = direction of current flow.
For right hand rule: I used FBI - thumb= direction of applied force, index finger = direction of magnetic field and middle finger = direction of induced current
AC would use Fleming's right hand rule because a current is induced as well as being produced by a generator.

Just very comfusing as I have come across videos saying that the two fingers are the opposite way around for right hand rule

On a quick search, I have not found any references that swap the fingers in the way you mention. Please post a link to an example or two.

haruspex said:
On a quick search, I have not found any references that swap the fingers in the way you mention. Please post a link to an example or two.
They're videos: and I can't find the other one.

Daniel2244 said:
They're videos: and I can't find the other one.

Ok.
The video provides a right hand rule applicable to a motor. You are used to using a left hand rule for motors, hence the need to swap the fingers. Confusing, but correct.

Daniel2244
haruspex said:
Ok.
The video provides a right hand rule applicable to a motor. You are used to using a left hand rule for motors, hence the need to swap the fingers. Confusing, but correct.
Thanks for clearing it up for me :) I tried looking in comments for reason he did it like but only found poeple with the same question. Also would the right hand rule be applied to the AC production? I would think so just want to double check.

Daniel2244 said:
would the right hand rule be applied to the AC production?
The right hand rule in the form you are familiar with applies to a generator, yes.
To get the rule for a motor you either swap hands or swap fingers.

Daniel2244
haruspex said:
The right hand rule in the form you are familiar with applies to a generator, yes.
To get the rule for a motor you either swap hands or swap fingers.
Ok thanks

Daniel2244 said:
Ok thanks
Not to nag but if current flows away from you and the magnetic field is towards the right the the direction of force is up but when the current/voltage changes polarity and becomes negative would the direction of force be down

Daniel2244 said:
Not to nag but if current flows away from you and the magnetic field is towards the right the the direction of force is up but when the current/voltage changes polarity and becomes negative would the direction of force be down
Yes.

Daniel2244

## 1. How does Fleming's left hand rule work?

Fleming's left hand rule is used to determine the direction of the force acting on a current-carrying wire in a magnetic field. The thumb, index finger, and middle finger of the left hand represent the direction of the magnetic field, the current, and the resulting force, respectively.

## 2. What is the difference between Fleming's left and right hand rule?

Fleming's left hand rule is used for determining the direction of the force acting on a current-carrying wire, while Fleming's right hand rule is used for determining the direction of the induced current in a conductor moving through a magnetic field.

## 3. Can Fleming's left and right hand rule be used interchangeably?

No, Fleming's left and right hand rule cannot be used interchangeably as they are used for different purposes. Using the wrong rule can lead to incorrect results.

## 4. What are the applications of Fleming's left and right hand rule?

Fleming's left and right hand rule are commonly used in electromagnetism, such as in electric motors and generators, to determine the direction of forces and currents in magnetic fields. They are also used in the study of electromagnetic induction and electromagnetic waves.

## 5. Are there any limitations to using Fleming's left and right hand rule?

One limitation of Fleming's left and right hand rule is that it only works for current-carrying wires or conductors moving through a magnetic field. It cannot be used for stationary charges or magnetic fields. Additionally, the rules only give the direction of the force or current, not the magnitude.

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