How do capacitors filter out different radio stations?

Question

and how do you know what capacitance filters you need to filter out different frequencies?

and why does this work?

Answer 1

capacitors them selves dont filter differen't radion stations. We used different filter circuits that have been designed to tune into a certain frequency. A popular method in cheap radios is to use a phase lock loop PLL) to select the frequency. filters are designed based on what frequency u want and what gain/attenuation u want. filters are either low pass, band pass, band stop or high pass. the simplest filter is an RC circuit where the voltage across the capacitor contains the frequencies below the cutt- off frequency. all otheres are attenuated. To better understand what ive said, do a google search on am radio circuits and you'll see what i mean

Answer 2

The traditional way to select a station is to use a capacitor and inductor (coil) in a parallel or serial circuit.  Because of the effect of the capacitor and inductor on the phase of the radio signal, there is a certain frequency that is passed, and others are blocked.  This filtering can also be done, now, by a phase locked loop, which avoids having to use a coil.  With the tuned circuit (capacitor and inductor), the tuned frequency is the one where the reactance of the two components is the same, which is at 1/(2pi√LC), where L is the inductance and C is the capacitance.  For more info, search for "tuned circuit."

Answer 3

The impedance of a capacitor is dependent upon frequency (Z = 1/(jwC)).  A capacitor blocks DC signals (frequency (w)= 0) because the impedance is infinite, and no current can pass through the device.  However, non-zero frequency signals create a finite impedance, which allows current through.  A passive low-pass or high-pass filter can be constructed using just a capacitor and a resistor.  These low-pass and high-pass filters are how "capacitors filter out different radio stations."  The frequencies that are filtered depend on the transfer function of the filter.