Calculate the magnetic flux density

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The discussion focuses on calculating the magnetic flux density (B) around a small coil near a large air-cored electromagnet. The participants analyze the relationship between charge flow, resistance, and the number of turns in the coil, emphasizing the importance of expressing resistance in terms of the coil's length and the resistance per unit length. They derive formulas to express B in terms of known variables, ultimately arriving at the correct calculation of B as 0.2 T. The conversation highlights the necessity of understanding the geometry of the coil and the relationships between its dimensions and electrical properties. This collaborative effort leads to a clearer understanding of the problem and its solution.
  • #31
TSny said:
Keep in mind that L is the length of the wire in the coil (because you need the resistance R of the wire). L is not the length of the cylinder on which the wire is wound. If you had to make a coil of N turns by winding wire around a cylinder of radius r, what length of wire would you need?
L = N 2 π r?

B = Q N 2 π r u / π r2 N = Q 2 u / r that gets B = 0.2 T. Thank you!
 
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  • #32
moenste said:
L = N 2 π r?

B = Q N 2 π r u / π r2 N = Q 2 u / r that gets B = 0.2 T. Thank you!
Yes, that's it.
 
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