# Magnetic field from two wires

1. Oct 15, 2014

### Jstuff

You have two wires an equal distance above and below the x axis the top wire comes out of the page and the bottom wire goes into the page.
Finally, consider point X (not shown in the diagram) located on the x axis very far away in the positive x direction. Which of the vectors best represents the direction of the magnetic field created at point X by wire 1 alone?
Hey guys I am confused on this problem I know the answer is the field will point in the positive Y direction, but I do not understand why.
I thought it would point in the positive x direction because of the right hand rule.
How does the fact that the particles are at a very far distance effect the direction of the magnetic field since the direction of the field would not change it would just become weaker. Right?

2. Oct 16, 2014

### Staff: Mentor

Sketch a set of axes, and mark on it the top wire, and point X far to the right.

3. Oct 16, 2014

### Jstuff

I've done this. From this and using the right hand rule the magnetic field would point along the x axis. How does the fact that it is very far away on the axis change the direction of the magnetic field?

4. Oct 16, 2014

### RUber

What is the direction of propagation? What direction is the electric field?
The way I understand this, your E field will be oriented with the wire (+Z), and propagation is in the (+X) direction.

5. Oct 16, 2014

### Jstuff

Well the direction of propagation to my understanding is to the right in the +X direction. However, the answer is that it propagates in the +Y direction from the top wire which I do not understand.