Ferrite cores are designed to block destructive analogue radio frequency interference on signal cables and power cords. Given the penetration of digital, High Definition Multimedia Interface (HDMI) cabling with flat screen televisions, the need for ferrite beads on these cables is less than in the days of analogue equipment. However, ferrite beads are useful on power cords, which can serve as antennas for RF intrusion. Adding a ferrite bead or two is an inexpensive yet effective tweak any flat panel owner can perform.
Unsnap the two halves of the ferrite core with your fingers, exposing the channel inside.
Lay the flat panel's power cord into the channel, 2-3 inches from the flat panel end of the cord.
Fold over the ferrite core, snapping the small latches back together. Add a second ferrite core 2-3 inches from the AC prong end of the flat panel power cord for additional filtration.
If the interference is severe, you may have to slide the core(s) up and down the cable until the best effect is achieved. You can loop the power cord around the ferrite core to "lock" the core in place.