Find Current in RC Circuit w/ V=Vo Sin(ωt)

AI Thread Summary
The discussion focuses on calculating the current in an RC circuit with a sinusoidal voltage input, V = V_o sin(ωt). The user attempts to derive the current phasor for the capacitor, \hat{I}_{C}, using impedance calculations and phasor relationships. There is uncertainty regarding the phase angle, ø, particularly whether it is zero since the current through the resistor, I_{R}, is said to be in phase with the voltage. Other participants suggest clarifying the source voltage representation and express concerns about the accuracy of the user's approach. The conversation highlights the complexities of phasor analysis in AC circuits while emphasizing the urgency of the user's exam preparation.
TheEvenfall
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Hello there, I'm not sure if my solution is correct for \hat{I}_{C}

Homework Statement



In the given circuit, calculate the current in each circuit element given that V = V_{o}sin(ωt)
R, L and C are given.
http://imgur.com/yO3flg8

Homework Equations


Z = R + jX (j^{2} = -1)
X_{L} = jωL
X_{C} = \frac{-j}{ωC}
\hat{V} = V_{o}e^{jωt}
\hat{I} = I_{o}e^{j(ωt-ø)}
I_{o} = \frac{V_{}}{|Z|}
tan(ø) = \frac{\Im(Z)}{\Re(Z)}

The Attempt at a Solution


First for the impedance, 1/Z_{XL} = 1/X_{L} + 1/X_{C}
Z_{XL} = j\frac{ωL}{1- ω^{2}CL}
Z = R + Z_{XL} = R + j\frac{ωL}{1- ω^{2}CL}
The current phasor in the resistor R: \hat{I_{R}}= \hat{I}= \hat{I_{C}} + \hat{I_{L}}
\hat{V_{C}} = \hat{V} - \hat{V_{R}}
\hat{I_{C}} = (\hat{V} - \hat{V_{R}} )/X_{C}
\hat{I_{C}} = (V_{o}e^{jωt} - I_{o}e^{j(ωt-ø)})(jωc) = V_{o}ωCe^{jwt}(1-\frac{R}{|Z|}e^{-jø})(j)
\hat{I_{C}} = V_{o}ωCe^{j(ωt+\pi/2)}(1-\frac{R}{|Z|}e^{-jø}) ø and |Z| are known.
AndI_{L} can be found the same way.
I'm not entirely sure my solution is correct. Also, since I_{R} is always in phase with V, does that mean that ø is 0? If so, then tan(ø) is also 0 but that would mean that either ω or L are 0...

Note: sorry if it seems slobby and for the skipped steps, my exam is in less than 3 hours and I'm really nervous and running out of time.
 
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Good luck with your exam! Don't worry too much about this last exercise. The assumption Ir is in phase with V seems incorrect to me.
 
well I'm still working through it, but one thing I want to point out is your source voltage is wrong. e^iwc =cos(wc) +isin(wc)
if you want to use eulers id. you want (e^iwc - e^-iwc)/2 , but that seems unnecessary, i'd just keep it v_s or something until you have your final answer, then sub in V(not)sin(wt). also it looks like complex analysis only? no time dependent ? just wondering.
 
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