A long, straight telephone cable contains six wires, each carrying a current of 0.300A. The distances between wires can be neglected.
A) If the currents in all six wires are in the same direction, what is the magnitude of the magnetic field 2.70 m from the cable?
B) If four wires carry currents in one direction and the other two carry currents in the opposite direction, what is the magnitude of the field 2.70 m from the cable?