resonance in RLC circuit

Discussion in 'Electrical Engineering' started by tbone, Dec 5, 2003.

1. tboneGuest

could someone explain what resonance is?

what is the difference between near resonance and practical resonance ?
what is the natural frequency of a circuit and what is omega (w) ? when
does a beat pattern occur ?

and what is the signal that has resonance ? the source ? the current ?
the voltage in a parallel cicruit ?

could you describe what a graph of this function look like ? (is it
sinusoidal, but always bigger magnitude ?)

thanks

I'm going to do this all wrong and people are DEFINATELY going to pick
holes, BUT...
in an RLC circuit, it's when the impedance of the capacitor and inductor
"cancel" - their imaginary components (jw) cancel.
not a scoobies!
"omega r" (wr) is the resonant frequency in radians/sec. This is often
termed the "natural frequency"
For beating to occur, you need two slightly different frequencies - take the
analogy of a guitar being tuned; as the note your tuning approaches a
reference, you can hear a beating frequency.
The frequency response of a resonant circuit has a large peak at w0. The
rest of the graph depends on the circuit in question.

3. tboneGuest

so much for a group about electrical engineering

4. Null SetGuest

Hi tbone,

You can probably find some good descriptions of resonance in electrical
circuits by doing a search on the Internet. I went to Google
(http://www.google.com), typed in "electric circuits resonance" without
quotes and found a pretty good site right off the bat,

http://www.ibiblio.org/obp/electricCircuits/AC/AC_6.html

and another one,

http://www.intuitor.com/resonance/circuits.html

If you'd prefer books, I'd recommend _Schaum's Guide to Electric Circuits_
by Edminster. _Engineering Circuit Analysis_ by Hayt and Kemmerly, and
_Network Analysis_ by Van Valkenberg as excellent sources.

To really understand resonance it helps to be able to understand the
mathematical models used in the standard descriptions. The typical math
model for a simple RLC resonant circuit involves a second-order linear
ordinary differential equations with constant coefficients. If you need
help with understanding what that means, find an introductory text
(sophomore college level, usually) on ordinary differential equations and
they'll usually talk about resonance when they get to solution of
second-order ordinary differential equations whose auxiliary equations have
complex conjugate solutions.

Also, realize that resonance is not just a phenomenon observed in electrical
circuits, but also in many types of physical systems. For example, most of
the texts I've seen on linear systems theory you'll see electrical
parameters (resistance, capacitance, etc.) compared with mechanical,
thermal, and fluid systems. The math is the same for certain arrangements
of elements in each type of system.

Try looking up some of this information on your own and ask the question(s)
again if you still have them after that.

Good luck and happy holidays,

-MC