Behaviour of charged particle.

[arul_k]

A charged particle moving through a uniform magnetic field experiences a force perpendicular to the direction of motion due to the magnetic field created around the charged particle. I would like to know if the particle were stationary and a uniform magnetic field moved past it would the nature of the force experienced by the particle be the same? If yes, would it imply that the interaction of the magnetic field with the particle is responsible for the magnetic field around the charged particle and not the motion of the particle itself? Naturally, the motion of the particle and field would have to be measured against some fixed reference frame.

 

[tiny-tim]

… if the particle were stationary and a uniform magnetic field moved past it would the nature of the force experienced by the particle be the same? If yes, would it imply that the interaction of the magnetic field with the particle is responsible for the magnetic field around the charged particle and not the motion of the particle itself?

Hi arul_k!

I'm not completely understanding the question, but anyway if an originally purely magnetic field B is moved, it becomes a mixture of a magnetic field B' and an electric field E' …

B' has no effect on the particle (because it's stationary), and the entire effect is caused by E'.

 

[arul_k]

Hi arul_k!

I'm not completely understanding the question, but anyway if an originally purely magnetic field B is moved, it becomes a mixture of a magnetic field B' and an electric field E' …

B' has no effect on the particle (because it's stationary), and the entire effect is caused by E'.

so in other words there would not be any affect due to the uniform magnetic field

 

[tiny-tim]

so in other words there would not be any affect due to the uniform magnetic field

Yup! No effect due to the new uniform magnetic field.

 

[arul_k]

Yup! No effect due to the new uniform magnetic field.

Okay. Thanks, but I was wondering dosen't the relative motion between the magnetic field and the charged particle play a part in the interaction, after all the charged particle has no way of "knowing" whether it is moving or the uniform magnetic field is moving, so why should there be two different results.

 

[tiny-tim]

Okay. Thanks, but I was wondering dosen't the relative motion between the magnetic field and the charged particle play a part in the interaction, after all the charged particle has no way of "knowing" whether it is moving or the uniform magnetic field is moving, …

ah, but the charged particle always thinks it's stationary!

so there's no choice to make …

it sees a mixed magnetic and electric field anyway.

(for example, if you study an electron "orbiting" a nucleus, you can't explain Thomas precession properly unless you measure the electromagnetic field from the point of view of the electron)

… so why should there be two different results.

There aren't … the result is the same, whether we regard the electron as moving or stationary.

 

[arul_k]

There aren't … the result is the same, whether we regard the electron as moving or stationary

.

Could you explain this further please. Thanks

 

[tiny-tim]

Could you explain this further please. Thanks

Sorry, I don't see what there is to explain …

what happens to the charged particle is the same, whichever frame of reference we choose.

Why do you think the results would be different? ​