Magnetism between two electrical wires

1. Nov 27, 2008

dimpledur

1. The problem statement, all variables and given/known data
Point P is midway between two long parallel straight wires that run north-south in a horizontal plane. The distance between the wires is 1 cm. Each wire carries a current of 1 A toward the north.

a) find the magnitidue and direction of the magnetic field at point P.
b)repeat a but assume the current in the wire on the east side runs towards the south instead.

3. The attempt at a solution

Okay, so for a), this is what I did.

I drew a diagram and concluded at point P there would be two magnetic fields due to the two electrical wires, that are equal and opposite in direction.

b) drew another diagram and concluded the same thing. The answer is 0.

Is that the proper way to approach a question like this?

2. Nov 27, 2008

naresh

One of your diagrams is wrong, try redrawing them.

This is the proper way to approach the problem, if the fields are indeed of equal magnitudes and opposite directions. If this turns out not to be the case, you will have to calculate the fields.

3. Nov 27, 2008

dimpledur

Got it, when the currents are in opposite directions, the magnetic fields interfere with each other in such a way that I simply superimpose them by addition. Correct?

4. Nov 27, 2008

naresh

Yup, that's right.

(In general, the fields are vectors, and the result is the vector sum of the fields. If they are equal and opposite, the vector sum is zero)