How can I create a magnetic field that is as homogeneous as possible?
Universities and schools sometimes ask how to create a homogeneous magnetic field for experiments.
In a homogeneous magnetic field, the lines of force are parallel and the magnetic field is equally strong in all places.
To create a magnetic field that is as homogeneous as possible, it is recommended to place two large magnets
close to each other and to connect the back sides with an iron yoke.
There will be a reasonably homogeneous field in the gap between the magnets.
The smaller the gap and the larger the magnets, the more homogeneous the field will be.
In the example we used two COLOSSUS
with a side length of 40 mm and a height of 20 mm.
We ordered the metal yoke at the local blacksmith.
The magnets are 10 mm apart from each other and the magnetic flux density between the magnets is approx.
0,95 tesla (= 9 500 gauss).
Caution: If you want to build such a "horseshoe magnet" yourself, you need to be extremely careful when attaching the magnets.
They much rather stick to each other than to the iron yoke.
It is extremely difficult to get the magnets into position with the aid of wooden planks and various screw clamps and without injuring yourself.
Alternative construction
An alternative and less dangerous construction could look like the one pictured here:
Legend
1: Two iron pieces
2: An aluminium block between the iron pieces to maintain distance between the two parts. This could, of course, also be another non-ferromagnetic material such as brass, wood, stainless steel, etc.
3: Block magnet (or several)
4: The more or less homogeneous magnetic field is created in this air gap between the two iron pieces
1: Two iron pieces
2: An aluminium block between the iron pieces to maintain distance between the two parts. This could, of course, also be another non-ferromagnetic material such as brass, wood, stainless steel, etc.
3: Block magnet (or several)
4: The more or less homogeneous magnetic field is created in this air gap between the two iron pieces
Alternative with enhanced flux density with smaller usable room.
In this version, both pole faces come together in a pyramid-shape.
That enlarges the flux density in the air gap.
This way, you can create flux densities that are much larger than those of the used magnets.