# Potentially silly question re magnetism....

• essenmein
In summary: An accelerating charge experiences a force in the opposite direction to the acceleration, due to the Lorentz force.
essenmein
The unit for flux density (a derived SI unit) is Tesla, this can be expressed as T = N*s/C*m.

Ie a particle with charge of 1 coulomb, traveling at 1m/s perpendicular to a magnetic field of 1Tesla experiences a force of 1N.

So my question, and this is more for my understanding since I'm not questioning Maxwell's equations!

Since moving charge is what essentially creates a magnetic field (ignoring displacement current for now, all though this is still something I don't fully understand), is this taken into consideration in the equation?

Or is it precisely the interaction of the two fields, the 1T field the particle is traveling through and the field the moving charge is creating that cause this force to be experienced by both the particle traveling and an opposite force on the thing making the magnetic field?

This question I guess is coming from the thought that the traveling 1 coulomb charge is creating its own field, and therefore due to vector addition of the two fields, the 1 coulomb charge would not be in a uniform 1T field any more purely due to its presence.

I think your answer is: a particle does not interact with its own field. Compare the situation of your moving charge in a B field with electrostatics: a test charge sitting at some point only 'feels' the fields from other charges.

Essenmein, you might have Lorentz' Law in mind.
##F=qvB##.

essenmein
However, to go along your thinking, the magnetic field that the moving charge would create would be circular. So, only part of the circular field would be canceled by the perpendicular magnetic field thus leaving the other part of the circular field to make it move. And that other part is would be in the direction of the perpendicular magnetic field, thus you would be back at Lorentz' Law.

essenmein
Would the following statement be correct:The forces experienced by a charged particle either in motion in a static magnetic field or stationary in the presence of an electric field, is due to the field interactions between the particles, not the fields interacting with the particles themselves.

Ie an uncharged particle, eg neutron, is not able to create a magnetic or electric field, and therefore cannot interact with them, therefore no forces experienced?

essenmein said:
Ie an uncharged particle, eg neutron, is not able to create a magnetic or electric field, and therefore cannot interact with them, therefore no forces experienced?
A neutron has a magnetic dipole moment.

essenmein
Dr_Nate said:
A neutron has a magnetic dipole moment.

Did not know that! Off to wiki I go...

AlexCaledin
BvU said:
I think your answer is: a particle does not interact with its own field.
May I suggest that when I accelerate a charge, I feel a force opposing me, which arises because I am pushing the charge against its own field, which I have distorted. The work I do against this force is equal to the radiated energy.

essenmein
tech99 said:
May I suggest that when I accelerate a charge, I feel a force opposing me, which arises because I am pushing the charge against its own field, which I have distorted. The work I do against this force is equal to the radiated energy.

Cool this is basically what I thought, but couldn't quite put my finger on an explanation.

There is a big difference between an accelerating charge and a moving charge

## 1. How does magnetism work?

Magnetism is a force that is created by the movement of electric charges. It is caused by the alignment of electrons in atoms, which creates a magnetic field. This field can attract or repel other magnetic objects.

## 2. What is the difference between a permanent magnet and an electromagnet?

A permanent magnet is made of a material that is naturally magnetic, such as iron or cobalt. It retains its magnetism without the need for an external power source. An electromagnet, on the other hand, is created by passing an electric current through a coil of wire. It can be turned on and off by controlling the flow of electricity.

## 3. Can magnets lose their magnetism over time?

Yes, magnets can lose their magnetism over time due to factors such as exposure to high temperatures, strong magnetic fields, or physical damage. This process is known as demagnetization. However, some materials, such as neodymium, retain their magnetism for a very long time.

## 4. How can I tell which end of a magnet is north and which is south?

One way to determine the north and south poles of a magnet is to use a compass. The end of the magnet that points towards the Earth's north magnetic pole is the north pole of the magnet. Another way is to suspend the magnet from a string and observe which end points towards the north when it comes to rest.

## 5. Can magnets attract or repel non-magnetic objects?

No, magnets can only attract or repel other magnetic objects. Non-magnetic objects, such as wood or plastic, do not have the necessary alignment of electrons to be affected by a magnetic field.

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