How far from this current-carrying wire will the Earth's magnetic field cancel the B-field from the wire?

[Bolter]

Homework Statement

Calculate the distance the neutral point is from the wire

Relevant Equations

Magnetic field strength due to current currying wire = u0 * I/(2*pi*d)

Hey everyone

So this is question shown below

I'm not so sure where to begin with this, but I thought I'd work out the net magnetic field first

How would I work out the magnetic field strength that is acting on the vertical current-carrying wire. Since I do not know what d is in this case?

Any help would be really appreciated! Thanks

 

[bluemystic]

Since the wire is vertical, the magnetic field produced by the wire should not be vertical, but horizontal. The vector you draw for Bv is vertical, I think that's why you're stuck.

 

[Bolter]

Since the wire is vertical, the magnetic field produced by the wire should not be vertical, but horizontal. The vector you draw for Bv is vertical, I think that's why you're stuck.

Ok so that means to find the net magnetic field strength. I know that both the magnetic field produced by the current carry wire and horizontal magnetic field are both horizontal and facing the same direction

This gives me the net magnetic field as this

I'm still not entire sure what to do with this net magnetic field expression to find the distance from neutral point?

EDIT: nevermind I think I have answered it now. I had equate B–wire = B–horizontal not sum them up together

 

[Merlin3189]

Summing them is fine if you then equate the sum to zero. You get the same equation.

BTW did you work out the direction before Chester told you?

 

[Bolter]

Summing them is fine if you then equate the sum to zero. You get the same equation.

BTW did you work out the direction before Chester told you?

Sorry for the late reply. Yeah I figured but then I had seen the post after correcting me.

I get 0.027m as my answer

 

[Merlin3189]

Looks right to me.