Illustrating the Direction of a Current in a Magnetic Field

[thaalescosta]

This is the question:
At a certain location in the Philippines, Earth’s magnetic field of 39 µT is horizontal and directed due north. Suppose the net field is zero exactly 8.0 cm above a long, straight, horizontal wire that carries a constant current. What are the magnitude and direction of the current?

I had no problem finding the magnitude of the current, but I'm struggling with visualizing the direction of the current. I didn't really understand what "horizontal and directed due to north" meant.

Is anyone able to illustrate what is going on with the magnetic field and how the wire is affecting the field?

Thanks

 

[composyte]

Alright so your basic plan of attack is to use the right hand rule. If there is a magnetic field pointing north and there is a wire running perpendicular to it: in what direction must the current flow to have its magnetic field oppose the one already present? I hope this rephrasing helps you some.

 

[thaalescosta]

Alright so your basic plan of attack is to use the right hand rule. If there is a magnetic field pointing north and there is a wire running perpendicular to it: in what direction must the current flow to have its magnetic field oppose the one already present? I hope this rephrasing helps you some.

This is how I'm visualizing. The answer says the current flows from west to east, but I don't see how the magnetic field is being canceled by the current.

 

[Bystander]

Map it by cm increments.

 

[thaalescosta]

Map it by cm increments.

what do you mean

 

[Bystander]

Eight cm, nine cm, ... seven cm.

 

[thaalescosta]

Eight cm, nine cm, ... seven cm.

I know, but I don't see how that would help me with the visualization. I have it scaled on paper, but I still don't get why the direction of the current must go from west to east instead of the opposite

 

[Bystander]

Is the conductor above or below the zero-field height?

 

[thaalescosta]

Is the conductor above or below the zero-field height?

The wire carrying the current is 8cm below the point where the net field is equal zero.

 

[Bystander]

right hand rule

don't see how the magnetic field is being canceled by the current.

Only at one point.