Difference between a ferromagnet and a paramagnet?

[ultimateguy]

I'm doing a presentation on magnetic hysteresis, and I have a feeling one of the profs will ask me what is the difference between a ferromagnet and a paramagnet. I haven't taken my 3rd year E&M class yet, so I would just like to know what I should answer.

 

[StatMechGuy]

Ferromagnets are permanent magnets and paramagnets are not. This is probably the simplest and most important distinction.

 

[Gokul43201]

Ferromagnets are permanent magnets

Not quite true. A ferromagnet with a large remanence makes a good permanent magnet. A ferromagnet with a small remanence (ie: a soft ferromagnet) does not make a good permanent magnet.

 

[Claude Bile]

Ferromagnets contain magnetic dipoles that 'influence' other dipoles around them, allowing them to align with one another. This property results in an enhanced magnetic response, as there is a reduced random variation in dipole orientation.

Claude.

 

[ultimateguy]

Ferromagnets contain magnetic dipoles that 'influence' other dipoles around them, allowing them to align with one another. This property results in an enhanced magnetic response, as there is a reduced random variation in dipole orientation.

Claude.

And how do paramagnets behave? Are the dipoles just completely random?

 

[Gokul43201]

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/magpr.html#c3
http://hyperphysics.phy-astr.gsu.edu/hbase/solids/ferro.html#c1

If you are to give a presentation on hysteresis, you need to first understand the basics of magnetism in solids. I suggest you get a good text from your library (eg: Rado & Suhl) and work from there.

 

[Meir Achuz]

I'm doing a presentation on magnetic hysteresis, and I have a feeling one of the profs will ask me what is the difference between a ferromagnet and a paramagnet. I haven't taken my 3rd year E&M class yet, so I would just like to know what I should answer.

In a paramagnet, the magnetization (M) is can be given as M=\chi H where
\chi is positive. In a ferromagnet, M and H are almost unrelated, and M is much larger than H in magnitude. The use of \chi in ferromagnetism is meaningless, altough some engineers try to use it.