Pleease explain uniformity of B in circular loop ?

[kira506]

Why is the magnetic flux density uniform at the center of the circular loop ?

 

[Meir Achuz]

It is not uniform. It varies in all directions. B is nearly uniform in the center of a long solenoid.

 

[jtbell]

Magnetic field of a current loop:

http://www.netdenizen.com/emagnettest/offaxis/?offaxisloop

For points in the plane of the loop, set x=0 and consider only B_x; B_r=0.

 

[Baluncore]

As you move towards one part of the circumference you are moving away from another at 180° to the first. The rise from one tends to cancel the fall from the other, so the field is remarkably smooth and gently curved near the axis.

 

[kira506]

It is not uniform. It varies in all directions. B is nearly uniform in the center of a long solenoid.

Thank you so much for you help , so its not uniform ... My textbook is really mistaken about almost everything >.< but what can I do ... You said that its nearly uniform at the center of the solenoid , so its not completely ? How so ?

 

[kira506]

Magnetic field of a current loop:

http://www.netdenizen.com/emagnettest/offaxis/?offaxisloop

For points in the plane of the loop, set x=0 and consider only B_x; B_r=0.

thank you so much , that was really helpful !

 

[kira506]

As you move towards one part of the circumference you are moving away from another at 180° to the first. The rise from one tends to cancel the fall from the other, so the field is remarkably smooth and gently curved near the axis.

Thank you so much , your simplified explanation was extremely helpful , thank you sincerely !

 

[Baluncore]

The attached screen dump shows two things. Firstly a circular loop of short filamentary segments, and secondly the B field measured across the circle, but very slightly offset from the plane of the circle which reduces the extreme peaks close to filaments.

If you want a 3D volume of reasonably uniform magnetic field you can use two plane loops in an arrangement called a Helmholtz coil. https://en.wikipedia.org/wiki/Helmholtz_coil

 

[kira506]

The attached screen dump shows two things. Firstly a circular loop of short filamentary segments, and secondly the B field measured across the circle, but very slightly offset from the plane of the circle which reduces the extreme peaks close to filaments.

If you want a 3D volume of reasonably uniform magnetic field you can use two plane loops in an arrangement called a Helmholtz coil. https://en.wikipedia.org/wiki/Helmholtz_coil

Thanks ، I think I understand now , thank you so much for the Helmholtz example ,realky helped