Inductive reactance is proportional to frequency...
XL = 2 pi f L
... so, the higher the frequency, the higher the reactance. At a sufficiently high frequency, the inductor would appear to be an open circuit. Note, however, that at very high frequencies, parasitic capacitance becomes a factor.
First, capacitance is the resistance of something to a change in voltage. And capacitance exists anywhere there is a conductor that is insulated from another conductor. With that definition, anything...
You typically create a DC power supply from the low frequency, and use that to run a high frequency oscillator and amplifier. If there needs to be a relationship between frequency in and frequency...
Rac is allways greater than Rdc due to skin effect which in
diactes less the freq less will be inductance and the
current will pass throug the entire cross sec area of
conductor.