Net magnetic field from two parallel conductors on a third

[EvaBugs]

I have a small question about net magnetic field.

If I have 3 straight conductors that are parallel where
-the current is to the left in conductor #3 (and situated at a distance b from #2)
-the current is to the right in conductor #2. (and is situated at a distance a from #1)
I have to find the net magnetic field exerted by #2 and #3 on the first conductor.


Using RHR I found that:
-conductor #3 , the magnetic field is directed out of the page;
-Conductor #2, the magnetic field is into the page.


To find the net magnetic field, should I use B= KI2/(b+a) - KI2/a

Thank you in advance

 

[OlderDan]

Are the conductors arranged in the order of number? #2 between #1 and #3? And was it supposed to say

-the current is to the left in conductor #3 (and situated at a distance b from #1)

and

I have to find the net magnetic force exerted by #2 and #3 on the first conductor

 

[EvaBugs]

Yes, it's supposed to say that. They are placed on top of the other.

 

[OlderDan]

If I am reading it right, the denominator a+b should be b itself. Are you looking for just the magnetic field, or the force on wire #1?

 

[EvaBugs]

For the net B on wire #1

-the current is to the left in conductor #3 (and situated at a distance b from #2)
-the current is to the right in conductor #2. (and is situated at a distance a from #1)

 

[OlderDan]

For the net B on wire #1

-the current is to the left in conductor #3 (and situated at a distance b from #2)
-the current is to the right in conductor #2. (and is situated at a distance a from #1)

Then the b+a should be correct

If #1 is on top, then your field directions are reversed. If #1 is on the bottom you have them right

 

[EvaBugs]

Yes, it is at the bottom

Thank you