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
Messages
3
Reaction score
0
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.
 
Physics news on Phys.org
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.
 
Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)'
I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8. I want to understand some issues more correctly. It's a little bit difficult to understand now. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. In the page 196, in the first paragraph, the author argues as follows ...
Thread 'Inducing EMF Through a Coil: Understanding Flux'
Thank you for reading my post. I can understand why a change in magnetic flux through a conducting surface would induce an emf, but how does this work when inducing an emf through a coil? How does the flux through the empty space between the wires have an effect on the electrons in the wire itself? In the image below is a coil with a magnetic field going through the space between the wires but not necessarily through the wires themselves. Thank you.
Back
Top