Calculating Magnetic Field Between Parallel Wires

[viperassasin]

Homework Statement

Two parallel wires are 5.60 cm apart and carry currents in opposite directions, as shown in the figure.

Find the magnitude of the magnetic field at point P due to two 1.50-\,{\rm mm} segments of wire that are opposite each other and each 8.00 {\rm cm} from P.

Homework Equations

The Attempt at a Solution

I don't know what to us for r or I'm using the wrong equation

but i used muenot Itop/(2pi r) + muenot I bottom/(2pi r) where r was the sqrt(8^2 +8^2)

 

[Phlogistonian]

I think you should use the Biot-Savart Law.

 

[Nick89]

Find the magnitude of the magnetic field at point P due to two 1.50-\,{\rm mm} segments of wire that are opposite each other and each 8.00 {\rm cm} from P.

Can you rephrase that line so it is readable? I don't know what they are asking now...

If they're asking the magnetic field for only small segments of the wire than yes, use Biot-Savart.

If they're asking the magnetic field for large segments of the wire (nearing infinite in relation to the other distances) then you can probably use Ampere's law ( int B * dl = ...)

 

[viperassasin]

got it

I can't post pics yet. but i got it anyway I was using the wrong thing for r on each magnetic field.