The two long straight wires are separated by a distance of d = 0.40 m. The currents are to the right in the upper wire and to the left in the lower wire. What is the direction of the magnetic field at point P, that is a distance d/2 below the lower wire?

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Explanation:

At point P, Using right hand rule, the direction of magnetic field  due to current flowing towards left in lower wire comes out to be in outward direction.

At point P, Using right hand rule, the direction of magnetic field  due to current flowing towards right in upper wire comes out to be in inward direction.

we know that magnetic field at a point by a long current carrying wire depends inversely on the distance from the wire. hence greater the distance, weaker will be the magnetic field.

Since point P is farther from upper wire and closer to lower wire, the magnetic field in Outward direction by the lower wire is stronger as compared to the magnetic field by the upper wire in inward direction.

hence magnetic field at point P comes out to be in Outward direction.