Which of the following is correct regarding the nature of parallel and anti-parallel currents?
Parallel currents attract and antiparallel currents repel.
When two straight conducting wires carry current in the same direction they are called as parallel currents and when they carry current in opposite directions they are called anti-parallel currents. For parallel currents shown in (a), we can see that the field produced (using the right-hand thumb rule) for the two wires almost blend together. Just like a magnet where opposite poles attract, here the different directions of the field act as different poles. Hence parallel currents attract while anti-parallel currents repel each other.