View Single Post
JCBII
JCBII is offline
#1
Feb18-13, 12:29 PM
P: 2
It's been many years since I studied this so I would appreciate some confirmation on the formula and its parts.

The formula I was taught to calculate the Gauss of an electromagnet was: B=MNI/2R
with: B = Magnetic flux in Gauss
M= Magnetic permeability of core material
N = Number of turns of wire
I = Current input in Amps
2R = two times radius (or diameter) of core

Question... is this formula correct?

I have noticed that the term Tesla is favored over Gauss. As I recall, 1 Tesla equals 10,000 Gauss. Am I correct?

I have been quoted by a metal manufacturer that the magnetic permeability of Nickle-Iron is 1,000,000 (one million). That same manufacturer said that NdFeB was 900,000. Do these numbers represent μ? Are these figures proper inputs for the above formula?

So lets create a hypothetical electromagnet. We'll use a .25" diameter by 12" long Nickle-iron rod as the core.

Using 24 Ga magnet wire (.0201") we can wind a coil 12" long by 7" in diameter. This would equal 220,000 turns of wire. If we then supply it with 500 mA of current it should look like this:

B = 1,000,000 x 220,000 x .5 / .25

B= 110,000,000,000 / .25

B = 440,000,000,000 or 440 Billion Gauss


Here's my problem:
The Mag Lab outside Tallahassee Florida claims to have built the world's strongest electromagnet which is 45 Teslas (450,000 Gauss) in strength.

So where have I screwed up in this calculation?
Phys.Org News Partner Physics news on Phys.org
Physicists design quantum switches which can be activated by single photons
'Dressed' laser aimed at clouds may be key to inducing rain, lightning
Higher-order nonlinear optical processes observed using the SACLA X-ray free-electron laser