Solving a Series LRC Circuit with Complex Impedances

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SUMMARY

The discussion focuses on solving a series L-R-C circuit with complex impedances, specifically determining the ratio Vout/Vin. The impedance Z is defined as Z = sqrt((IR)^2 + (I*X_L - I*X_C)^2), where X_L and X_C represent the reactances of the inductor and capacitor, respectively. The solution requires applying Kirchhoff's Voltage Law (KVL) without the need for Laplace transforms, emphasizing the use of complex numbers for impedance. Understanding the 'dot' notation in the circuit diagram is crucial for measuring voltages across terminals.

PREREQUISITES
  • Understanding of series L-R-C circuits
  • Knowledge of complex impedance and reactance
  • Familiarity with Kirchhoff's Voltage Law (KVL)
  • Basic calculus skills (Calc 2 level)
NEXT STEPS
  • Study the concept of complex impedance in AC circuits
  • Learn how to calculate the reactance of inductors and capacitors
  • Explore Kirchhoff's laws in the context of AC circuits
  • Investigate alternative methods for circuit analysis, such as phasor analysis
USEFUL FOR

Electrical engineering students, circuit designers, and anyone interested in analyzing AC circuits using complex impedance methods.

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Homework Statement


A series L-R-C circuit consisting of a voltage source, a capacitor of capacitance , an inductor of inductance , and a resistor of resistance is driven with an AC voltage of amplitude and frequency . Define to be the amplitude of the voltage across the resistor and the inductor.

FIND THE ratio Vout/Vin

picture: http://www.chegg.com/homework-help/questions-and-answers/series-l-r-c-circuit-consisting-voltage-source-acapacitor-capacitance-inductor-inductance--q416667?frbt=1

Homework Equations



Z = sqrt((IR)^2+(I*X_L-I*X_C)^2)

The Attempt at a Solution



I found Vin = sqrt((IR)^2+(I*X_L-I*X_C)^2)

Then I googled the question for Vout and tried to use kirchhoffs voltage and loop rule. I only found solutions using laplace transforms or something - I am in calc 2.

Any kind of hint in the right direction would be nice. I don't understand the 'dot' notation on the circuit. And the whole problem is really throwing me in circles.
 
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In a circuit, open circles are usually used to represent points (terminals) at which you measure a voltage. In this case, they've used closed circles instead, and they're just indicating that Vout is the voltage measured between these two terminals.

That's all the dots are.
 
You don't need to use Laplace transforms. You can just use KVL and solve the circuit normally, except that you need to use the impedance of each component which, in general, is a complex number.

What is the expression for the impedance of an inductor? How about a capacitor?

Since this is a series circuit, what is the current in terms of the source voltage and the impedances?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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