# Anti Parallel Currents and Magnetic Field

1. Feb 23, 2005

Two long parallel wires are a distance of d = 4.5 cm apart and carry equal antiparallel currents of 1 Amperes. Find the magnetic field intensity (in T) at the point P which is equidistant from the wires. (R = 2 cm).

Now I really thought I had this. I thought the magnetic field at P would be the superposition of the vectors of the magnetic fields from each of the two wires. After working with the equations I figured out the net magnetic field was in the positive x directions with magnitude B=(2kId)/(x^2), where k=(Mo/4pi), I=1 A, d=4.5cm, and x=2cm. I get the wrong answer. Why?

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2. Feb 24, 2005

### Gamma

check the value of x.

x = 3 cm.

$$x=\sqrt(R^2 + (d/2)^2)$$