Neutrons in electromagnetic fields

In summary: The magnetic field from the wire might be zero at the location of the neutron, but the force on the magnetic dipole can still be nonzero. This is what is happening in the Stern-Gerlach experiment - the force on the magnetic dipole is nonzero even though the magnetic field is zero.
  • #1
Danyon
83
1
Consider a moving neutron passing by an electromagnet, will a neutron be deflected? This video seem to show that the neutron would have to be charged in order for it to move
 
Physics news on Phys.org
  • #2
This video seem to show that the neutron would have to be charged in order for it to move
How? When?

Note: Objects do not have to have a charge to be deflected by a magnet.
http://www.phys.utk.edu/witek/np621/symmetrytests.pdf
... see section on neutron spin: they are little magnets.
... directly after that, see the brute force measure for neutron neutrality.
 
Last edited by a moderator:
  • #3
Simon Bridge said:
How? When?

Note: Objects do not have to have a charge to be deflected by a magnet.
http://www.phys.utk.edu/witek/np621/symmetrytests.pdf
... see section on neutron spin: they are little magnets.
... directly after that, see the brute force measure for neutron neutrality.
The video implies that the neutron would have to be charged at 2:44 The proton in the video moves because it is electrostatically repelled by the length contracted Protons in the wire. A neutron, being neutral, cannot experience this force.
 
Last edited by a moderator:
  • #4
If a neutron were to experience the force being illustrated, then it would have to be charged. But there is nothing there to indicate that the neutron experiences the force being illustrated.

Basically you are noticing that the video is incomplete.
Did you read the link?
 
  • #5
Simon Bridge said:
If a neutron were to experience the force being illustrated, then it would have to be charged. But there is nothing there to indicate that the neutron experiences the force being illustrated.

Basically you are noticing that the video is incomplete.
Did you read the link?
"Objects do not have to have a charge to be deflected by a magnet." I was aware of this, I was just pointing out that the mechanism described in the video seems to imply that neutrons won't deflect, when they should, showing that the special relativity explanation is inconsistent with reality,
 
  • #6
"Objects do not have to have a charge to be deflected by a magnet." I was aware of this, I was just pointing out that the mechanism described in the video seems to imply that neutrons won't deflect, when they should, showing that the special relativity explanation is inconsistent with reality,
... or that the short introductory demo in a youtube video is somehow incomplete...

BTW: what makes you think that neutrons deflect in the circumstances described in the video?
 
  • #7
Simon Bridge said:
... or that the short introductory demo in a youtube video is somehow incomplete...

BTW: what makes you think that neutrons deflect in the circumstances described in the video?
I just thought so since they have magnetic moments,
 
  • #8
Work it out - would a neutron, in the situation that the video places a proton, be deflected by the magnetic field of the wire?
 
  • #9
Simon Bridge said:
Work it out - would a neutron, in the situation that the video places a proton, be deflected by the magnetic field of the wire?
I'l say no, however, it must be deflected by permanent magnets which work on a different principle
 
  • #10
Permanent magnets use electromagnetism just like electromagnets do.
You cannot do physics by analogy - try using maths (or experiment).

In the link I gave you it shows you that neutrons are not deflected by a uniform electric field - which would need to be the case for the circumstances in the video above to show a contradiction. A neutron can be deflected by a non-uniform magnetic field - as int he Stern-Gerlach experiment. The field about a wire is non-uniform in the direction the field points in - like it is in the S-G apparatus. That is not the case for the wire.

You may want to get together with this person:
https://www.physicsforums.com/threads/two-velocities-in-the-lorentz-law.804172/
... you are studying the same video. Perhaps you are in the same class?

It will also benefit you to get other sources.
 
  • #11
"Permanent magnets use electromagnetism just like electromagnets do." This video seems to imply that it's the intrinsic magnetic moment rather than the effects of special relativity
 
  • #12
Danyon said:
"Objects do not have to have a charge to be deflected by a magnet." I was aware of this, I was just pointing out that the mechanism described in the video seems to imply that neutrons won't deflect, when they should, showing that the special relativity explanation is inconsistent with reality,
You have to be careful not to overgeneralize small concepts. In the video they are specifically discussing the magnetic force on a point charge outside a current carrying wire. They are not even talking about the magnetic field. The magnetic force can always be made zero by transforming to a frame where the point charge is at rest, but that does not imply that the magnetic field is zero nor does it imply that the force on a magnetic dipole could be made zero.
 

1. What are neutrons in electromagnetic fields?

Neutrons in electromagnetic fields refer to the behavior and interactions of neutrons, which are subatomic particles, in the presence of electromagnetic fields. These fields can be created by electric charges or magnetic fields.

2. How do neutrons behave in electromagnetic fields?

Neutrons do not have an electric charge, so they are not affected by electric fields. However, they do have a magnetic moment and are therefore affected by magnetic fields. The direction of the neutron's magnetic moment determines its behavior in the field.

3. What is the significance of studying neutrons in electromagnetic fields?

Studying neutrons in electromagnetic fields is important for understanding the fundamental properties of neutrons and their interactions with other particles. It also has practical applications in fields such as nuclear physics, materials science, and medical imaging.

4. How are neutrons in electromagnetic fields used in medical imaging?

Neutrons can be used in medical imaging techniques, such as neutron radiography and neutron tomography. These methods use the interaction of neutrons with the body to create images that can reveal information about the internal structure and composition of tissues and organs.

5. Are there any risks associated with neutrons in electromagnetic fields?

Neutrons themselves do not pose a significant risk, as they are not ionizing radiation. However, if neutrons are used in nuclear reactions, they can produce secondary radiation that can be harmful. It is important to carefully control and shield these reactions to minimize any potential risks.

Similar threads

  • Special and General Relativity
Replies
5
Views
985
  • Special and General Relativity
Replies
34
Views
1K
  • Special and General Relativity
Replies
8
Views
924
Replies
6
Views
882
  • Special and General Relativity
Replies
24
Views
1K
Replies
8
Views
766
  • Special and General Relativity
Replies
17
Views
670
  • Special and General Relativity
Replies
31
Views
474
  • Special and General Relativity
Replies
8
Views
791
  • Special and General Relativity
Replies
4
Views
384
Back
Top