# Equation of a Magnetic Field of a Solenoid

1. Aug 14, 2013

### eigenstaytes

I'm a Physics student currently working on some research with my advisor. My advisor doesn't know much about modeling solenoids so I've been tasked with reaching outside for help. I did that, but I can't remember the formula or the guy's name so I'm turning to you guys for help.

There is some formula that is of the format

$B_{center}=(Current Density)*radius*F(\alpha, \beta); F(\alpha, \beta) = \ln\frac{something_{1}}{soemthing_{2}}$

If I remember correctly, this came about by some french guy who had integrated the Biot Savart law and came up with this. His name started with an F. I had it written down on a piece of paper with the guy who gave it to me, but I seem to have lost that paper. He said that it is used in engineering purposes since the biot savart law is used for the physics behind it. He pulled it out of Superconducting Magnets by Martin Wilson.

Can someone please help me re-find this so I can use it and I don't look like a fool by having to ask him again?

Thanks!

2. Aug 19, 2013

### Carl Pugh

The book Physics by Hausmann-Slack has 5 1/2 pages on the derivation of the flux density on the central portion of a straight solenoid.
Physics book gives the field intensity as H=4PiNI/10l
H=field intensity in oersteds
Pi=3.14
N=Number of turns
I=current in amp.
l=Length in centimeters

3. Aug 20, 2013