Two long, straight wires are parallel and 16 cm apart. one carries a current of 2.9 a, the other a current of 5.7 a. (a) if the two currents flow in opposite directions, what is the magnitude (in n/m) and direction of the force per unit length of one wire on the other?

Explanation:

Given that,

Distance between two long wires, d = 16 cm = 0.16 m

Current in one wire,

Current in wire 2,    

The magnetic force per unit length of one wire on the other is given by the following expression as :

The current is flowing in opposite direction, the magnetic force acting on it is repulsive. Hence, this is the required solution.