When two wires have current in same direction then force is

Two proton beams going in the same direction repel each other whereas two wires carrying currents in the same direction attract each other. Explain.

Two proton beams going in the same direction repel each other whereas two wires carrying currents in the same direction attract each other. Explain.

Two proton beams going in the same direction repel each other whereas two wires carrying currents in the same direction attract each other. Explain.

Two long parallel straight wires, each carrying a current of 2 A are placed at distance of 3 cm. Calculate the force acting per unit length of each wire. Also, state the nature of force between the wires if the currents flow in the same direction in both the wires.

Two long parallel conducting wires carry current I in same direction, placed at distance b. Force per unit length of wire is