ferrite bead inductance
Originally functioning as a frequency-dependent resistor, they present a very high impedance to the higher frequencies necessary for noise suppression. As advertised ferrite beads function primarily to eliminate high-frequency noise, while at the same time allowing DC to pass through. Most fundamentally, ferrite beads are a kind of frequency-dependent resistor. At higher frequencies, the bead offers very high impedance- this is the key to noise suppression. The constructions of ferrite beads can be divided into two general types, round prhaps a bit more common and cylindrical either style is equally acceptable though preference should be left up to the user In technology, ferrite beads are made of a ceramic material containing iron oxide, which give them their unique magnetic properties. This design enables them to accept high levels of electrical current without suffering serious losses in power. In applications, they are simply everywhere. As noise filters on power supply lines or data cables; wherever unwanted high-frequency signals might interfere with the normal operation of electronic devices.
