Magnetic Field Axial Rotation

Experiment to show that the field of a permanent magnet does not rotate with the magnet along the B axis.

Category:

Science & Technology

Tags:

• Magnet
• Field
• B-Vector
• Axial
• Rotation

[helpmonkey]

theory ... magnitism is two dimentional... what we see as a megnetic field is polarity caused by spin... we can only measure magnitism when there is a polarity ... polarity can only be present in three dimensional space...therefore does a magnetic field rotate with an objec? ... hmm ... in reference to the two dimensional magnetism I would say no .... in reference to the three dimensional polarity I would say yes... again just a theory *<:0)

[AdminOnDuty]

@helpmonkey ,

Hi :)

I think Maxwell and Heaviside as well as Tesla all felt the magnetic field was 3D or even 4D (including time). You may find youtube user, SirZerp's work enlightening on this matter:

watch?v=XT3NrFfQclg&feature=pl­ayer_profilepage

Also youtube user, Pinestonemtn has some interesting videos as well:

watch?v=byxCYvDjFRM

Did you notice also, the effect when the magnet is drawn to and from the screen?

What if we used two magnets

[forevereternal22]

So basically if that were the case then starting rotating a magnet along its axis as a homopolar motor would not generate current. However it does generate current. Because the electrons starting from a stand still must experience a change in flux to be compelled forward. Even though that flux remains of equal flux density along the axis of rotation. Basically what I am saying is you are not rotating the magnet fast enough along its axis to see any effect.

[AdminOnDuty]

@forevereternal22

Thanks for your thoughtful response ;-)

When conventional current flows in a homopolar motor wire, it leaves the center of the battery positive and moves radially outward across the variant magnetic field. This produces a force that is perpendicular to the current flow and perpendicular to the B field. This also occurs along the edge of the battery because the field is not uniform along that edge, so a force exists there as well.

What do you think the force pushes against?

[MercJ777]

The reason that you are you do not see a change is because the magnetic field of the magnet is evenly distributer and as you can see from the reaction of your camera the monitor it is not, that is why you get those straight lines. My understanding of tvs/monitors is that they have an electron gun at the back firing at the phosphorus on the the front of the screen in successive lines which are stationary normally on a horizontal orientation. The weak magnetic equator cant induce a change

[AdminOnDuty]

@MercJ777

The camera "bars" are caused by timing interference in the framing of the screens.

The magnetic patterns are produced by interactions of the screen components and the induced magnetic fields that interaction produces. The electrons take a different path when they travel through the field and this is what causes the patterns as the electrons hit different phosphor than they were intended to. The fact that the patterns do not change as the magnet is rotated, shows axial symmetry for B

[forevereternal22]

ahem... I mean rotation of magnetic flux around the central axis of the magnetic field

[forevereternal22]

If you are correct and I do not believe you are.  Then how would you explain how a homopolar motor rotates along the axis of the magnetic field. I believe the only working explanation is that there is rotation of magnetic flux even along the axis.

[AdminOnDuty]

@MercJ777

The reason is because the flux angle and flux density is the same for any give radius from the center of the magnet all the way around.

You are correct that many TV's and Monitors have Cathode Ray Tubes that have electron guns and this is true of the one used in the video. However, the 'stationary' lines are a product of our eyes persistence of vision coupled with the photo-emissive phosphor. If you had a fast enough camera, you would see that they are really only successive dots.

[AdminOnDuty]

@100mButterfly ,

The reason there is no rotation is because the cross section of the field that intersects the screen (Gaussian surface) is symmetrical in a circle around the center of the pole. For any radius from that center, the flux is the same around the circumference of that radius. The CRT electron interaction with that flux will only change if the flux magnitude or the angle of the flux changes. Since neither of these things change during rotation the pattern does not change. ;-)