RC Filters

High-pass and low-pass filters can be made from RC networks.
In the high pass filter, low frequencies are blocked by the capacitor (C), but high frequency signals are transferred to the output.
In a low-pass filter, high-frequency signals are routed to ground while low-frequency signals are sent to the output.

The impedance of element C-Xc (resistance change with frequency) decreases with increasing frequency. At low frequency, the impedance increases: Xc is found by the formula:
Xc= 1 / (2πfC)

When the f (frequency) frequency signal is applied, which provides the R=Xc equality in both circuits, the end point of the permeability is observed. That is, low f or high f is calculated with the formula R=Xc.