What is the small cylindrical object of the power cord?

First of all, this small cylindrical object is deliberately installed. Their nickname is ferrite beads or ferrite chokes. Their sole purpose is to reduce electromagnetic interference and RF interference. The simple point is to reduce unnecessary signal or noise. As we all know, when two electromagnetic devices are connected by cable, the cable acts as an antenna. So the problem is, like all antennas, these cables can also receive and propagate signals from other unrelated devices. The result is noise or interference from unwanted signals.

This is the necessity of ferrite beads, which eliminates broadcast signals and ensures that cables do not send any other intrusive signals outside the program.

If you open these bumps, you will find a small cylindrical solid made of ferrite, which is inherently magnetic.

Ferrite is made of iron oxides (i.e., rust) combined with other metals, black, hard and brittle. But its magnetism can effectively eliminate interference.