Is There a More Accurate Equation for the Magnetic Moment of a Solenoid?

AI Thread Summary
The discussion centers on finding a more accurate equation for the magnetic moment of a solenoid that does not rely on the number of turns. The participant is validating a solenoid with approximately 11,000 turns and seeks an alternative method to calculate the magnetic moment using measured magnetic flux. They mention that while a dipole approximation is commonly used, it is not ideal since a solenoid behaves like a dipole only at infinity. The participant provides a formula for the magnetic moment in Gaussian units, m=BAL/4pi, but notes that the units are unconventional and suggests that the magnetic constant may need to be included for clarity. The focus remains on deriving a formula that accurately reflects the magnetic moment without depending on the number of turns.
Kydharis
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Does anyone have an equation that describes the magnetic moment of a solenoid that does not actually use number of turns as an input?

I'm trying to validate a solenoid I have made with something like 11000 turns, but I'm not sure how accurate my number of turns in, so I need a second input that I can validate through testing (In this case, I can measure the magnetic flux at the poles of the solenoid).

I'm told that using a dipole equation for it is a decent approximation, but I'm really looking for a better approximation than that, since ideally a solenoid only becomes like a dipole at infinity.
 
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The B field on the axis at one end of a solenoid is 1/2 what is given by the standard formula for the B field at the middle of a long solenoid.
 
Yes, but unfortunately the standard formula for the B field of a long solenoid has a
dependence on N (turns).

I actually can measure B of my solenoid - its the magnetic moment I'm concerned about. I want to use the B field I measured to get a magnetic moment.
 
In Gaussian units, the magnetic moment of a solenoid of length L with a field B at its center is m=BL/4pi.
 
I left out the cross-sectional area of the solenoid.
The mag moment should be m=BAL/4pi.
 
The units on that equation are a little weird. Right now, BAL/4pi is Tm^2 (or gauss*M^2). In my experience, magnetic moment is usually given in Am^2. I think the missing link is the magnetic constant - but adding it in with the 4pi leaves us with Am^3.
 
It may be shown from the equations of electromagnetism, by James Clerk Maxwell in the 1860’s, that the speed of light in the vacuum of free space is related to electric permittivity (ϵ) and magnetic permeability (μ) by the equation: c=1/√( μ ϵ ) . This value is a constant for the vacuum of free space and is independent of the motion of the observer. It was this fact, in part, that led Albert Einstein to Special Relativity.
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