# Magnetic field density

1. Mar 18, 2006

### thebigcheese

In physics we are learning about Magnetic fiex densities and have been taught that that the symbol for Magnetic flux density is B, however I cannot find where this letter comes from.

I know 'I' came about because they fought it was the 'intensity' of current and didnt know any different.

However if anyone can shed any light about where or what B stood for I would be very grateful.

2. Mar 21, 2006

### Meir Achuz

That is an interesting question to research historically.
In Maxwell's treatise (1873), he used the German script B for
what he called "magnetic induction" and the German script H for what he called "magnetic force". I consider both terms archaic today.
He does not indicate why he uses B and H, but gives a reference
(with no details) to Sir William Thomson.
You would have to go back to before Maxwell to find out who and why chose B (or H). Try researching Faraday or Ampere.

3. Apr 3, 2006

### Cermander1

umm...hi

I'm currently a physics student in 11th grade. My teacher would give us extra credit if we find out why "B" is used for Magnetic Field strength. I've been looking for it for hours and i'm completely stumped. I'm beginning to believe there is no reason. Pretty cruel joke...

4. Apr 4, 2006

### Meir Achuz

Your teacher probably knows the answer. Please post it here when he tells you. You could try going to the library and looking through biographies of Faraday and Amper.

5. Sep 11, 2006

### thebigcheese

Still no answer. Looking it up I have found another magnetic thingy is 'wb' prehaps they just dropped the w?

6. Sep 11, 2006

### Staff: Mentor

"wb" (abbreviation for "weber") is the SI unit of magnetic flux, which nowadays has the symbol $\Phi$ or $\Phi_B$. It's named after the German physicist Wilhelm Weber.

7. Sep 11, 2006

### Meir Achuz

The "Weber" was chosen as a unit 100 years after Maxwell used B for Magnetic field. You might try looking in a German or Latin dictionary.

8. Sep 11, 2006

### denni89627

B (and H) may have been the first letters alphabetically that weren't in use when Maxwell was writing his equations. Just a guess.