# How is Fleming's left hand rule applied in Hall effect

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• Shafia Zahin
In summary, the explanation on Britannica.com states that in hall effect, a perpendicular magnetic field causes the moving charges to be displaced sideways in the same direction, regardless of whether the current is composed of positive, negative, or a mixture of both charges. This is because Fleming's left hand rule, which deals with conventional current, states that when both types of charges are involved, the direction of the force on negative charges will be the same as the direction of the force on positive charges. This rule takes into account the direction of current flow, rather than the type of charges involved.

#### Shafia Zahin

I've been reading the explanation of Britannica.com about the direction of magnetic force on a moving charge in hall effect.

"Whether the current is a movement of positive particles, negative particles in the opposite direction, or a mixture of the two, a perpendicular magnetic field displaces the moving electric charges in the same direction sideways at right angles to both the magnetic field and the direction of current flow."
I don't understand why does a positive and a negative charge feels the magnetic force in the same direction in the hall effect?Because as per the Fleming's left hand rule the moving positive and negative charges should feel the magnetic force in opposite directions.

When a current is flowing, and where both + and - mobile charges are involved, the direction of the force on the negative charges (flowing in one direction) will be the same as the direction of the force on positive charges (flowing in the opposite direction). Minus times minus = plus. Flemmings rule just deals with conventional current (the rule was made long before they found electrons, ions or holes). How that current is carried makes no difference to the result.

• Shafia Zahin
Shafia Zahin said:
per the Fleming's left hand rule the moving positive and negative charges should feel the magnetic force in opposite directions

If the + and - charges are moving in the same direction, the magnetic forces are indeed in opposite directions. However, the + and - charges must move in opposite directions, if the currents they produce are in the same direction. There are two "opposites": opposite charges and opposite directions.

• Shafia Zahin
Okay.Thank you all for the help.
I've understood the direction problem now.

## 1. How is Fleming's left hand rule applied in Hall effect?

The Fleming's left hand rule is used to determine the direction of the force acting on a current-carrying conductor placed in a magnetic field. In Hall effect, the rule is used to determine the direction of the electric field generated in a semiconductor material by the magnetic field.

## 2. What is the purpose of using Fleming's left hand rule in Hall effect?

The purpose of using Fleming's left hand rule in Hall effect is to understand and predict the behavior of electrons in a semiconductor material placed in a magnetic field. This allows scientists to study the properties of the material and make practical applications, such as in sensors and transistors.

## 3. How do you apply Fleming's left hand rule in Hall effect?

To apply Fleming's left hand rule in Hall effect, you need to follow these steps:

1. Extend your thumb, index finger, and middle finger perpendicular to each other.

2. Point your index finger in the direction of the magnetic field.

3. Point your middle finger in the direction of the current flow.

4. Your thumb will then point in the direction of the electric field that is generated by the Hall effect.

## 4. Can Fleming's left hand rule be applied in Hall effect for any type of material?

Yes, Fleming's left hand rule can be applied in Hall effect for any type of material as long as it is a semiconductor and has a current flowing through it. However, the strength of the electric field may vary depending on the properties of the material.

## 5. Are there any limitations to using Fleming's left hand rule in Hall effect?

One limitation of using Fleming's left hand rule in Hall effect is that it only works for a single charge carrier. In materials with multiple charge carriers, the direction of the electric field may not be accurately determined using this rule. Additionally, the rule assumes that the current is uniform throughout the material, which may not always be the case.