Example 4: Two long parallel wires separated by a distance \( d \) and carry currents \( I_{1} \) and \( I_{2} \) in the same direction.(a) Derive an expression for the magnetic force per unit length on one of the wires due to the other and show that, in keeping with Newton's third law, the forces on the two wires are equal in magnitude. (b) Show that for these current directions, the forces are mutually attractive, in keeping with Newton's third law that the forces are at action- reaction pair must be opposite in direction.
