Direction of magnetic field - moving charge

In summary, according to Maxwell, a moving charge will create a circular magnetic field perpendicular to the direction of travel. This means that the magnetic field will act in all perpendicular planes and loop around the line of motion. It will not create a force upward or downward on the moving particle due to its zero distance from itself. However, an external magnetic field can cause the particle to move in a circular path and provide centripetal acceleration if the initial velocity is perpendicular to the field.
  • #1
jsmith613
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Homework Statement


according to Maxwell a moving charge will create a magnetic field perpendicular to the direction of travel.
does this mean in ALL perpendicular planes (e.g: if the charge is moving to the left the magnetic field will act up, down, and side to side) or will it only act in one perpendicular plane. if it only acts in one plane then which plane will it act in?Also why does this magnetic field not create a force upward / downward... on the moving particle

Homework Equations


The Attempt at a Solution


I could not post in the other section so have posed my question above.
There is no more information I can add to show any better understanding than that above
 
Last edited:
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  • #2
hi jsmith613! :smile:
jsmith613 said:
… does this mean in ALL perpendicular planes (e.g: if the charge is moving to the left the magnetic field will act up, down, and side to side) or will it only act in one perpendicular plane. if it only acts in one plane then which plane will it act in?

the magnetic field is circular, it loops around the line of motion, see http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html for a pretty picture (and a thumbs-up) :wink:
Also why does this magnetic field not create a force upward / downward... on the moving particle

suppose there was another particle moving parallel to the first …

the magnetic field would make it go in a circle, but would not cause it to change its distance (though the electric field would, of course) …

the original particle is at zero distance from itself, and that won't change, so no upward or downward force

(is there any spinning force? i can't answer that :redface:)
 
  • #3

here is another question:
if we had an EXTERNAL magnetic field, the magnetic force would be applied ppd to the direction of motion. would this cause centripetal acceleration?
 
  • #4
a uniform magnetic field causes any charged particle to move with constant speed along a helix whose axis is parallel to the field

if the initial velocity is perpendicular to the field, then the helix becomes a circle (perpendicular to the field), and then yes the magnetic force will provide the centripetal acceleration :smile:
 
  • #5


Your understanding of Maxwell's equations is correct. A moving charge will create a magnetic field that is perpendicular to the direction of its motion. This means that the magnetic field will act in ALL perpendicular planes, including up, down, and side to side. The direction of the magnetic field will depend on the direction of the current flow, as determined by the right-hand rule.

As for why the magnetic field does not create a force upward or downward on the moving particle, this is because the magnetic force is always perpendicular to the direction of motion of the charged particle. This means that the magnetic force cannot change the speed of the particle, only its direction. In order for the magnetic field to exert a force in the upward or downward direction, there would need to be a component of the magnetic field that is perpendicular to both the direction of motion and the direction of the magnetic field. However, since the magnetic field is always perpendicular to the direction of motion, there is no such component and therefore no force in the upward or downward direction.
 

1. What is the direction of the magnetic field around a moving charge?

The direction of the magnetic field around a moving charge is perpendicular to both the direction of the charge's motion and the direction of the external magnetic field.

2. How does the direction of the magnetic field change with the speed of the moving charge?

The direction of the magnetic field is directly proportional to the speed of the moving charge. As the speed increases, the direction of the magnetic field also changes.

3. What happens to the direction of the magnetic field if the moving charge changes direction?

If the moving charge changes direction, the direction of the magnetic field also changes accordingly. It will always be perpendicular to the charge's current direction of motion.

4. Can the direction of the magnetic field be reversed around a moving charge?

Yes, the direction of the magnetic field around a moving charge can be reversed by reversing the direction of the charge's motion or by changing the direction of the external magnetic field.

5. How does the direction of the magnetic field around a moving charge affect nearby objects?

The direction of the magnetic field around a moving charge can affect nearby objects by exerting a force on them. This force can cause the objects to move or change their orientation.

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