# Finding the magnetic field strength

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1. May 4, 2015

### johndough999

1. The problem statement, all variables and given/known data
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.
2. Relevant equations
B = (μI/2πR) * r
B = μH

3. 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: May 4, 2015
2. May 4, 2015

### Hesch

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: May 4, 2015
3. May 4, 2015

### johndough999

Hi Hesch, to find the distance from the origin are you using the following formula?
√ X^2 + Y^2 + Z^2

4. May 4, 2015

### Hesch

No, I'm using r = √(x2+z2)

Plot the locations of the conductor and the origin in the plane: y = 0.

5. May 4, 2015

### johndough999

Thanks for the help hesch!