RLC Circuits - Q Factor and Amplitude

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SUMMARY

The discussion focuses on the differences in amplitude response between two RLC circuits with varying Q-factors when the driving frequency is altered. Circuit 1 has a high Q-factor (Q1 >> 1), indicating a sharper resonance peak, while Circuit 2 has a low Q-factor (Q2 < 1), resulting in a broader resonance peak. As the frequency moves away from resonance, the amplitude response will drop off more sharply for Circuit 1 compared to Circuit 2. Understanding the physical representation of Q and its impact on resonance behavior is crucial for analyzing these circuits.

PREREQUISITES
  • Understanding of RLC circuit fundamentals
  • Knowledge of Q-factor and its significance in resonance
  • Familiarity with amplitude response and frequency analysis
  • Basic proficiency in using oscilloscopes for measuring output voltage
NEXT STEPS
  • Study the relationship between Q-factor and resonance in RLC circuits
  • Learn how to graph amplitude vs. frequency for RLC circuits
  • Explore the impact of varying resistance on Q-factor and resonance behavior
  • Investigate qualitative vs. quantitative analysis in circuit resonance
USEFUL FOR

Electrical engineering students, circuit designers, and anyone interested in understanding resonance behavior in RLC circuits.

wjdgone

Homework Statement


Imagine you have two RLC circuits you are trying to scan for resonances. They have identical resonant frequencies, but circuit 1 has a very high Q-factor
(Q1 >> 1), and circuit 2 has a very low Q-factor (Q2 < 1). Let's assume you are already
on resonance and looking at V(out) on the oscilloscope, and you change the frequency in either direction for both circuits. How will the amplitude response differ between circuits 1
and 2 as you move the driving frequency away from resonance?

Homework Equations



Q=R/(2*pi*f*L) - not sure if I need this in the first place

The Attempt at a Solution


I don't think I understand what the problem means by "as you move the driving frequency away from resonance." My best blind stab in the dark for this problem is that Q1 means that R>2*pi*f*L and Q2 means that R<2*pi*f*L, and I can relate the inductance to the change in amplitude such that if inductance decreases, amplitude increases? (I'm also not sure how to relate inductance to amplitude.)
 
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wjdgone said:
not sure if I need this in the first place
You can use it if you know the definition of ##Q## and understand what they mean with ##\Delta \omega ## :rolleyes:
 
BvU said:
You can use it if you know the definition of ##Q## and understand what they mean with ##\Delta \omega ## :rolleyes:
I still don't understand how I can determine what amplitude does.
 
Since you are not given any values at all, I'd take this as a qualitative question rather than quantitative.
What you need to understand is what Q represents and how it relates to resonance behviour.
I expect many PF readers will be best able to get this from the formulae, but I find the simple notion of what Q represents physically, shown vividly in graphs of amplitude vs frequency, is the easiest way to understand what will happen in the situation described - and no calculations needed!
 

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