Two long wires each carrying a d.c. current in the same direction are placed close to each other. Which one of the following statements is correct?

When two long parallel wires carry direct current (d.c.) in the same direction, they generate magnetic fields that interact with one another. According to the right-hand rule, each wire produces a magnetic field that circles around it. The second wire, being placed within this magnetic field, experiences a Lorentz force. Ampere's force law and experimental demonstrations confirm that parallel currents flowing in the same direction result in an attractive force between the conductors. Conversely, if the currents were antiparallel (opposite directions), the wires would repel each other. This phenomenon is a fundamental principle of electromagnetism and is used to provide the operational definition of the ampere. The force is constant for steady d.c. currents and does not only occur during switching transients.