How can I calculate the magnetic moment of a solenoid with specific parameters?

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Discussion Overview

The discussion focuses on calculating the magnetic moment of a solenoid with specific parameters, including its dimensions, power supply, and current. Participants explore the implications of these parameters on the magnetic field intensity and related calculations for force applied to nearby objects.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant requests guidance on calculating the magnetic moment of an air gap solenoid with specified parameters, including voltage, turns, length, current, and flux density.
  • Another participant suggests modifying the solenoid design by placing the air gap inside the coil and minimizing its length for better performance.
  • A participant questions whether the orientation of the air gap (vertical vs. horizontal) affects the calculations, seeking clarification on the measurement of the gap distance.
  • A later reply emphasizes that the gap size should be measured along the field lines and should be small compared to the total length of the magnetic loop, indicating that the field strength is maximized when the gap is within the solenoid coil.
  • There is a formula provided for the magnetic field in the gap, expressed as B = u0NI/G, where G represents the gap size.

Areas of Agreement / Disagreement

Participants express differing views on the optimal placement and size of the air gap, as well as its orientation, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants have not reached consensus on the best approach to calculating the magnetic moment or the implications of the solenoid's design parameters, and there are assumptions regarding the definitions of terms like "gap" and "field lines" that remain unaddressed.

Jake110
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Could someone show me how to calculate the magnetic moment of a solenoid, it's an air gap solenoid, 12V power supply, 1200 turns, 6cm long, the current works out to around 5-7 A and uses 1mm wire (18 AWG or 19 SWG). the flux density works out at about 3 Teslas.

If what I'm using it for effects how you calculate it, I'm using it to work out the intensity of the magnetic field which I can then use to calculate the force applied to an object near the solenoid.
 
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Hi jake-
In the attached thumbnail, in fig B, reverse the location of the gap so it is inside the coil and as short as possible. A shorter gap is better. Also, the cross-sectional area of the permeable material outside the coil should be at least twice the cross-sectional area of the coil itself.
Bob S
 

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so I'm i getting this right, its the same if the gap is vertical through the coil from the top to the bottom? so then G would be the horizontal distance of the gap?
 
Jake110 said:
so I'm i getting this right, its the same if the gap is vertical through the coil from the top to the bottom? so then G would be the horizontal distance of the gap?
Hi Jake-
The size of the gap G is always the length measured along the field lines, and it should be small relative to the total length measured around the magnetic loop. The field in the gap is strongest if it is inside the solenoid coil.

B = u0NI/G Tesla in the gap.

Bob S
 

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