# Magnetic flux density

1. Feb 4, 2008

### unseensoul

magnetic flux density is denoted by the B symbol
magnetic flux is denoted by the $$\phi$$ symbol

so why do people use B as if they were referencing to magnetic flux?

"magnetic flux density is a measurable quantity indicating the strength of a field" ...this was stated by a teacher of mine...anyway, is true?

First, magnetic flux density isn't it the same as magnetic induction, i.e. magnetic flux per unit area perpendicular to the magnetic field?
Second, I thought that the strength of a field was denoted by H...

I've been searching throughout the internet and I found different meanings for the same thing which lead me to get more confused.

Best regards
-unseensoul

2. Feb 4, 2008

### TVP45

Here's a good start
http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.html

Just remember that, at a practical level, the magnetic field strength H is most useful when dealing with magnetic materials (soft iron, silicon steel, etc.).

If you just want a memory trick (not completely true), think of H as the cause and B as the result.

I'm sorry to give a 75% answer (i.e., not absolutely true), but I can't think of anyway short of about three hours to say it all. Perhaps another responder will have a more succinct answer.

3. Feb 9, 2008

### unseensoul

I've taken a look to it before I came here and it didn't help me :\

ps: I'm sorry to get you back so late...

4. Feb 10, 2008

### dst

B is magnetic flux density - keyword: density. As in, magnetic flux per unit area/volume. Phi is the total amount, i.e. in the same way that density * volume = mass.

Referring it to as magnetic flux is probably just a short hand way of going about things.

5. Feb 10, 2008

### unseensoul

I didn't mean that. What I'd like to know is why is the magnetic flux density referred as the magnetic field strength?

Thank you

6. Feb 10, 2008

### TVP45

Magnetic field strength is not the same as the magnetic flux density. They are proportional (the constant (?) of proportionality being permeability). If some source refers to them as the same, that source is incorrect.

7. Feb 10, 2008

### pam

The words describing magnetism can be ambiguous and vary over time.
It is best to use B and H instead of words, because the usages B and H are universal.