Two long straight wires are parallel and 8.6 cm apart. They are to carry equal currents such that the magnetic field at a point halfway between them has magnitude 370 µT. (a) Should the currents be in the same or opposite directions? (b) How much current is needed?

(a) The current should be in opposite direction

(b) The current needed is 39.8 A

Explanation:

Part (a)

Based, on right hand rule, the current should be in opposite direction

Part (b)

given;

strength of magnetic field, B = 370 µT

distance between the two parallel wires, d = 8.6 cm

At the center, the magnetic field strength is twice

R = d/2 = 8.6/2 = 4.3 cm = 0.043 m

Therefore, current needed is 39.8 A

magnitude and direction