# Help illustrating magnetic field line vectors and gradients

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1. Sep 22, 2015

### magnetics

Magnetic field lines around multipolar magnets get quite complex. There are local field vectors and field gradients in the x, y, & z plane. In the following diagrams I have tried to illustrate field lines around a centrally (half and half) charged disc magnet. The top diagram represents the field lines and the bottom the field gradients in the xy plane (assuming the xy plane in parallel to the surface and the z plane perpendicular).

I would love for learned PF magnetism experts to critique these illustrations. Thank you.

(I realise the colour of these field lines be swapped on the bottom)

2. Sep 22, 2015

Staff Emeritus
Magnetic field lines have no beginning or end. Your drawings show the opposite.

3. Sep 22, 2015

### vanhees71

Where are these drawings from? They are even worse than the usually not very accurate field-line pictures even in textbooks. Very good ones are in the good old book by Sommerfeld:

A. Sommerfeld, Lectures on theoretical physics, vol. 3 (electromagnetism)

Particularly you have to properly distinguish between $\vec{B}$ and $\vec{H}$ lines!