What current flows equally on all conductors of an unshielded multiconductor cable?

By definition, common-mode current is the component of an electrical signal that flows in the same direction, with the same phase and amplitude, along all conductors of a cable simultaneously. Because these currents travel in parallel and do not have an opposing return path within the cable to cancel their magnetic fields, they turn the entire cable into a radiating antenna. In contrast, differential-mode current is the intended electrical signal that flows down one conductor and returns via the other in opposite directions. These opposing currents cancel out each other's fields, preventing unwanted radiation. When dealing with unshielded multiconductor cables, suppressing common-mode current typically requires a common-mode choke, such as a ferrite core.