# Physics (urgent please)

posted by
**James P.**
.

Two parallel wires are carrying 5A and are separated by 2.0 m. if the currents are in opposite directions, what is the magnitude of the magnetic field halfway between them?

Someone please help as I can't figure out the question.

Thanks,

They are asking for the field between the wires, not the force.

Because of symmetry, the magnetic field due to each wire will be equal and in the same direction at any point midway between them. (If the currents were parallel, the fields would cancel there and the net would be zero). Just double the field due to one wire. That gives you

B = 2 * muo * I/(2 pi R)

where R = 1.0 m, a muo is the peremeability of free space.