Finding the magnetic field strength

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Discussion Overview

The discussion centers around calculating the magnetic field strength at the origin due to a current flowing in a specific direction and location. Participants explore the application of Ampere's law and the correct method for determining the distance from the origin, considering both theoretical and practical aspects of the problem.

Discussion Character

  • Homework-related, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant presents a calculation for the magnetic field strength using the formula B = (μI/2πr) and suggests that they may not be using the correct distance from the origin.
  • Another participant introduces Ampere's law and provides an alternative expression for H, indicating that the magnetic induction should be considered instead of B.
  • A question is raised regarding the formula for finding the distance from the origin, specifically whether to use the three-dimensional distance formula.
  • A different approach is suggested, where one participant states they are using a two-dimensional distance calculation that excludes the z-axis.

Areas of Agreement / Disagreement

Participants express differing views on how to calculate the distance from the origin, with some advocating for a three-dimensional approach and others for a two-dimensional one. The discussion remains unresolved regarding the correct method for determining the distance and the implications for calculating the magnetic field strength.

Contextual Notes

There are limitations in the assumptions made about the dimensions involved in the distance calculation, and the discussion does not resolve the mathematical steps necessary for a complete solution.

johndough999
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Homework Statement


There exists a current of 5A in the ay direction at x=2m,z=-2m where the ay is the unit vector in the y direction. Find the magnetic field strength at the origin.

Homework Equations


B = (μI/2πR) * r
B = μH

The Attempt at a Solution


B = (μI/2πr)
B= (4π*10^-7)(5)/2π(2)
where r is the distance from origin, in this case r=2m.
B=5*10^-7 T

I believe I am not finding the correct distance from the origin.Not using the z axis at all.
Thanks for the help!
 
Last edited:
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Amperes law:

Cirkulation ∫ Hds = N * I →

H = I / (2πr)

r = √(22+22) (pythagoras).

You should not find B, as it is the magnetic induction (flux-density).
 
Last edited:
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Hi Hesch, to find the distance from the origin are you using the following formula?
√ X^2 + Y^2 + Z^2
 
No, I'm using r = √(x2+z2)

Plot the locations of the conductor and the origin in the plane: y = 0.
 
Thanks for the help hesch!
 

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