A long straiht telephone cable contains six wires , each carrying a current of 0.5 A. The distance between the wires can be neglected.
a. If the current in all six wires are in the same direction, what is the magnitude of the magnetic field 10 cm from the cable ?
b. If four wires carry current in one direction and the other two in opposite directions, what is the field magnitude at 10 cm from the cable ?

Explanation

`6 xx 10^(-6) T b. 2 xx 10^(-6)` T