# Permanent Magnets

korneld
I have a few questions about permanent magnets:

What are the most powerful permanent magnets made of? How strong do they get?

What are the ways to make an already powerful magnet even stronger?

I understand that placing iron behind it will amplify it. Why?

I also read somewhere that shape is really important as well. What are the best shapes to make a magnet stronger? How does that work?

Thank you.

Kit
1. What are the most powerful permanent magnets made of? How strong do they get?
Ans: permanent magnet in fact is base on ferromagnetism. i think u can look it up here http://en.wikipedia.org/wiki/Permanent_magnet#Permanent_magnets
i dun know what is the strongest magnet in the world. but if u want to generate a very strong magnetic field, u can use a superconducting solenoid. Typically i can generate a B-field around 10Tesla.

2. What are the ways to make an already powerful magnet even stronger?
Ans: i think what u are talking about is to put a iron coil inside a solenoid to make a stronger B-field, rite? this is because the iron would confines the magnetic flux so the the magnetic flux density(B-field) increases.

3. What are the best shapes to make a magnet stronger? How does that work?

hope it helps^^

kit

daveb
The strongest I know of that are available are rare Earth magnets such as neodymium. I'm sure there are stronger ones (probably rare-earth) that could be made.

Oh, and the strongest magnetic fields ever discovered are in magnetars.

Last edited:
korneld

Kit:

This is the page where I read about steel increasing flux density and the shape being important: http://www.wondermagnet.com/magfaq.html#q71

Here is the quote:

"B (flux density): This is the measurement (in Gauss or Tesla) you get when you use a gaussmeter at the surface of a magnet. The reading is completely dependant on the distance from the surface, the shape of the magnet, the exact location measured, the thickness of the probe and of the magnet's plating. Steel behind a magnet will increase the measured 'B' significantly. "

It is also common for a magnet to be encased in steel when used in speakers, isn't it?

Also all solutions would have to be at room temperatures (and here on Earth )

The website referenced above also says that NdFeB (Neodymium-Iron-Boron) magnets are the strongest ones available today (a/ 1T). I was wondering if that was true.