Physics- finding the magnetic field ?

Question

In a figure, four long copper wires are perpendicular to the page, and their cross sections form a square of edge length a= 14 cm. The currents are out of the page in wires 1 and 4, and into the page in wires 2 and 3, and each wire carries 24 A. What is the net magnetic field at the square's center? (Take the positive direction of the z axis to be out of the screen. Use T for Tesla.)

PLease help me, ASAP!

Thanks in advance

Answer 1

From symmetry the magnetic fields at the center of the configuration of the currents in the wires going into the page cancel the magnetic  fields of the wires going out of the page. So the net field at the center is zero.



Here's how you would calculate the field of one wire.

Use Ampere's Law

B = (Uo)I/(2pi)r

where Uo = permeability of space = 4pi x 10^-7 T m/A

I = current in each wire = 24 A

r = distance from wire to point in question = .0989800 meters

For the 24 A current the B field =4.85 x 10^-5 Tesla at the center

Use the right hand rule to determine the direction of the B field for each wire.