# B-field at point P that is produced by the current in two wires

1. Mar 29, 2013

### AxM=Fam

1. The figure shows an end view of two long, parallel wires perpendicular to the xy-plane, each carrying a current I=5.00A but in opposite directions. What is the magnitude and direction of the B-field at point P that is produced by the current in the two wires?

2. B=(μo/4pi) integral from +infinity to -infinity (I/r^2)(dl x r^)
Biot-Savart Law
B=μoI/2pi(r)

3. I am having a very hard time trying to understand this problem; but this is my attempt which is not complete.
At first I was going to get my B total by Adding B1 + B2 getting each by using the second formula on top. This just doesnt seem right.
Second attempt was getting B1 and B2 using the second formula. Then to get the B field I was going to do B=sqrt of B1^2 + B2^2
but I cannot figure out how to get direction?

#### Attached Files:

• ###### BField.docx
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2. Mar 29, 2013

### Sunil Simha

Resolve the Magnetic field vectors ( along the axes) and then add them vectorially.

3. Mar 29, 2013

### rude man

Why not? Just pay attention to the signs.
2nd attempt - forget it! The fields add. The system is linear!