# Simple Question about the direction of magnetic induction

• titansarus
In summary, the conversation discusses a scenario where a copper wire is placed perpendicular to a 0.02 Tesla magnetic field and is moved with a velocity of 8 m/s. The goal is to find the induced emf and the location of the positive charge. Using the Lorentz law, it is determined that the positive charge moves in the direction of force, which is north in this case. The calculated emf is 0.04 volt when the wire is moving from east to west, and 0 when it is moving from west to east. However, due to a mistranslation, the correct direction of the wire is south-north, resulting in an emf of sqrt(2) * 0.02 when
titansarus

## Homework Statement

There is a magnetic field B=0.02 Tesla and its direction is toward the plane (perpendicular to plane, shown by X X X X X - I'm not sure how to say this direction in English,sorry). we have a copper wire (uniform bar) perpendicular to magnetic field from south to north. we move the wire with speed 8 m/s from west to east. We want to find the induced emf and the place where the positive charge is induced (north or south)

Length of wire=0.25 m
2. The attempt at a solution
I can calculate the first part easily with V = BLV and we get 0.04 volt. But I don't know how to determine the place where the positive charge is induced. How I should solve this?

Thanks in advance and sorry for my English.

Last edited:
titansarus said:

## Homework Statement

There is a magnetic field B=0.02 Tesla and its direction is toward the plane (perpendicular to plane, shown by X X X X X - I'm not sure how to say this direction in English,sorry). we have a copper wire (uniform bar) perpendicular to magnetic field from south to west. we move the wire with speed 8 m/s from west to east. We want to find the induced emf and the place where the positive charge is induced (north or south)2. The attempt at a solution
I can calculate the first part easily with V = BLV and we get 0.04 volt. But I don't know how to determine the place where the positive charge is induced. How I should solve this?

Thanks in advance and sorry for my English.
You didn't give L so we can't confirm your answer of 0.04V.

To get the charge locations, use the Lorentz law.

titansarus
rude man said:
You didn't give L so we can't confirm your answer of 0.04V.

To get the charge locations, use the Lorentz law.
Sorry, The L is 0.25 meter. Can you give more information about how to use lorentz law (If you mean F = q v cross b). It gives the force, how can I get the position of positive charge with that?

titansarus said:
Sorry, The L is 0.25 meter. Can you give more information about how to use lorentz law (If you mean F = q v cross b). It gives the force, how can I get the position of positive charge with that?
Charge goes in the direction of force does it not?
Your answer is incorrect. Think about tthe direction of the bar in relation to the direction of the velocity.

titansarus
rude man said:
Charge goes in the direction of force does it not?
Your answer is incorrect. Think about tthe direction of the bar in relation to the direction of the velocity.
The direction of force for q>0 is to north. so it means that positive charge goes to north,yes?

But I think v=0.04 volt is correct, Are you sure it is incorrect?

titansarus said:
The direction of force for q>0 is to north. so it means that positive charge goes to north,yes?
You must decide for yourself.
But I think v=0.04 volt is correct, Are you sure it is incorrect?
If the direction of the bar were east-west, i.e. along v, what would the emf be then?

titansarus
rude man said:
You must decide for yourself.
If the direction of the bar were east-west, i.e. along v, what would the emf be then?
Oh, the main question was in another language and I mistranslated it. It was meant to be south-north. for south-west, it is sqrt(2) * 0.02, and for east-west, 0, yes?

titansarus said:
Oh, the main question was in another language and I mistranslated it. It was meant to be south-north. for south-west, it is sqrt(2) * 0.02, and for east-west, 0, yes?
Carry out the vector expression emf = B⋅(L x v). (This also answers your first question).

## What is magnetic induction?

Magnetic induction is the process by which a magnetic field is created in a material due to the presence of an external magnetic field. This can occur through the movement of charged particles or through the alignment of magnetic domains.

## How is magnetic induction measured?

Magnetic induction is measured using a unit called the tesla (T). One tesla is equal to one weber per square meter (Wb/m2). A commonly used unit for magnetic induction is the gauss (G), which is equal to 0.0001 T.

## What is the direction of magnetic induction?

The direction of magnetic induction is always perpendicular to the direction of the magnetic field lines. This means that if the magnetic field lines are pointing towards the north, the direction of magnetic induction will be towards the east or west.

## How does the direction of magnetic induction affect a material?

The direction of magnetic induction can have a significant impact on the properties of a material. For example, in ferromagnetic materials, the direction of magnetic induction can determine the strength of the material's magnetization and its ability to retain a magnetic field.

## What factors can affect the direction of magnetic induction?

The direction of magnetic induction can be affected by the strength and orientation of the external magnetic field, the type of material, and the temperature of the material. Additionally, the presence of other magnetic fields or electrical currents can also influence the direction of magnetic induction.

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