Circuits - AC circuits / phasor

AI Thread Summary
The discussion focuses on the calculation of equivalent impedance and current magnitude in AC circuits, highlighting the importance of phase angles. The initial poster correctly identified the equivalent impedance and current magnitude but did not account for the phase angle θ in their calculations. It was clarified that while the phase angle is not provided, it is essential for accurate results. Participants noted that specifying the phase angle in terms of the impedance's angle is possible and necessary for complete analysis. The conversation emphasizes that understanding phase shifts is crucial in AC circuit calculations.
wcjy
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Homework Statement
Given the following circuit with the voltage source V=5 cos(t+θ) and the resistor R1=1.1(Ω) and the inductor L1=0.8(H). The impedance Z_eq of the circuit and the phasor current I can be respectively described as

$$Z_{eq} =a+jb $$
$$I= I_o ∠ Φ $$

Find a, b, and Io in these expressions.
Relevant Equations
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Hi, my school has no answer key provided. and would like to check if this is correct. Thanks!
 
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Hi. It looks like you've correctly found the equivalent impedance and the magnitude of the current (both without units though). However, you'll need to account for the phase angle θ of the source in your Io.
 
gneill said:
Hi. It looks like you've correctly found the equivalent impedance and the magnitude of the current (both without units though). However, you'll need to account for the phase angle θ of the source in your Io.
From the question, I_o is without phase angle. where I = I_o ∠ Φ. That is why i didn't account for the phase angle.

side note: how do you input latex for like I_o in the text
 
It's ##I_{0}## [sharp(#) sharp(#) I_{0} sharp(#) sharp(#) ]
 
wcjy said:
From the question, I_o is without phase angle. where I = I_o ∠ Φ. That is why i didn't account for the phase angle.
Presumably you'll need to specify what ##\Phi## is, no?
 
gneill said:
Presumably you'll need to specify what ##\Phi## is, no?
i don't need to but is it even possible, since they did not give angle ##\theta##
 
You need ##\theta## to compute ##\varphi##
 
wcjy said:
i don't need to but is it even possible, since they did not give angle ##\theta##
You can specify ##\Phi## in terms of ##\theta## and the impedance's angle.
 
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gneill said:
You can specify ##\Phi## in terms of ##\theta## and the impedance's angle.
Yes, phase shift matters in AC circuits.
 
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