# Permanent magnet questions

## Main Question or Discussion Point

Im looking to do some projects with permanent magnets.

I dont have access to a gaussmeter and i'm wondering if there are any sites that have representations, descriptions or formulas for the field strengths of ferrite or neodymium magnets.

Also i need to learn about how magnetic fields from permanent magnets interact with each other in attractive and repulsive situations containing mulitple magnets.

Im guessing im going to have a lot to learn as I have no formal physics education.

Any help enabeling me to understand this concept would be appreciated.

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Simon Bridge
Homework Helper
Welcome to PF;
The interactions of magnets is very complicated unless you strive to keep the geometry simple.
Computing the field strengths of magnets is also not easy.
So the details will depend a lot on what you want to do with them.

Manufacturers will often tell you a rated strength for their products - read carefully.

The equations for electromagnets and magnetic induction are (a bit) easier - if I were you, I'd use a coil of wire to measure field strengths and run it as an electromagnet to compare strengths.

Try the wikipedia articles for permanent and electro-magnets as starting points.

Hi Simon,

Thanks for the reply. So, I have a N35 neodymium magnet 12mm x 12mm x 6mm with north and south being on the opposing 12 x 12 faces. If I were to plot out in 3d space the strength of the field at that a particular point and assign a colour to that point (red and blue for example) to represent its polarity then I could build up a visual representation of the magnet and its field. If I then repeated this for 3 other magnets of the same grade and same size but with one dimension changed, say changing 6mm to 12mm then 24mm and lastly 48mm I would get a get a data set that I could then use to determine the strength and field shape of a magnet that is 16mm. Correct?

I'm hoping that I am correct and his has been done before and there is some formula that can calculate this without me having to purchase a gaussmeter and do it myself, it seems pretty basic.

I'm reading through the wiki also