Name of component on output side cable of a DC power adapter?
It's a ferrite choke, not going to retype it all but here's an article: What are the bumps at the end of computer cables?.

These &quot;bumps&quot; are called ferrite beads or sometimes ferrite chokes. Their goal in life is to reduce EMI (electromagnetic interference) and RFI (radio-frequency interference).
A ferrite bead is simply a hollow bead or cylinder made of ferrite, which is a semi-magnetic substance made from iron oxide (rust) alloyed with other metals. It slips over the cable when the cable is made, or it can be snapped around the cable in two pieces after the cable is made. The bead is encased in plastic -- if you cut the plastic, all that you would find inside is a black metal cylinder.