I searched both terms on Wiki
http://en.wikipedia.org/wiki/Self-Resonant_Frequency
and
http://en.wikipedia.org/wiki/Resonant_frequency
I still don't understand what is the difference between them. Let says,
what is the meaning of Self-Resonant Frequency in an Inductor compare
to Resonant Frequency of a Transducer?
Thanks.
Resonance (in electrical parlance) refers to the frequency where the
capacitive reactance is equal to the inductive reactance. At this
point, the phases cancel and you get a sharp change in the overall
impedance. For example, a parallel LC circuit (capacitor in parallel
with an inductor) will be in resonance at a frequency where 2*pi*f*L =
1/(2*pi*f*C). At this frequency, the impedance of this parallel LC
circuit will be extremely high due to the phase combination.
Normally, the term "self-resonant" frequency refers to the resonant
frequency of a component due to the parasitic characteristics of the
component. For example, the physical construction of a capacitor will
determine the parasitic inductance of the leads/connections to the cap.
The frequency where the capacitive reactance of the cap and the
inductive reactance of the lead's parasitic inductance, is the
self-resonant frequency. It is a property of the physical
characteristics of the device - and to some extent, defines where the
cap no longer behaves like a cap, but begins to behave like an
inductor.
When designing resonant circuits, you pick the capacitance and
inductance. Ideally, you will operate at frequencies that are far away
from the self-resonant frequency of the individual components. Of
course, there are special circumstances where you might do a design
that involves utilizing components near their self-resonant frequency,
but it isn't that common.