Understanding Energy in RLC Circuits: Initial Conditions

AI Thread Summary
In RLC circuits at resonance, the inductive reactance (Xl) equals the capacitive reactance (Xc), and the supply voltage is in phase with the current. At the initial moment, while the current is zero, the voltage across the inductor and capacitor reaches its maximum, indicating energy storage. The problem requires calculating the energy stored in these reactive components using specific formulas. It is important to note that t=0 does not imply the generator was just activated; it reflects a steady state prior to measurement. Understanding these concepts clarifies the energy dynamics in the circuit.
CH1991
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Homework Statement



Please check picture

http://i.imgur.com/YMQBR.png

YMQBR.png


Homework Equations





The Attempt at a Solution



Shouldn't all the energy be 0 at beginning?
Thanks!
 

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It tells you that this circuit is at resonance. Do you know what this means about the values of Xl, Xc and R.
 
Xl = Xc

R = R...
 
The question doesn't make much sense!
It is at resonance and that means:
1) Xl = Xc
2) Supply voltage and current are in phase
3) Supply voltage is the voltage across R
4) The power is dissipated in R
This means that you can calculate the value of R. You are given the resonant frequency so you can calculate Xc and therefore Xl.
I don't understand what they are asking !
 
The problem asks about the energy stored in the inductor and in the capacitor, when the current is zero, so the voltage across the reactive elements is of maximum magnitude. You need the formula for the energy stored in an inductor and in a capacitor.
t=0 does not mean that the source was switched on at that instant. The generator voltage has been the same before we started to measure time.

ehild
 
thank you!
 

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