Phase Angle between Voltage and Current

AI Thread Summary
The discussion revolves around calculating the impedance and phase angle between voltage and current in a circuit with a resistor and inductor connected to an AC generator. The impedance of the series combination was calculated to be 389.94 ohms. The phase angle can be determined using the formula cos(θ) = R/Z, where R is the resistance and Z is the impedance. Participants noted confusion about finding the inductive reactance (XL) but eventually clarified that Ohm's Law can be used to find R from the known voltage and current. The conversation highlights the importance of correctly identifying variables in the calculations.
theintarnets
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Homework Statement



"When only a resistor is connected across the terminals of an ac generator (111 V) that has a fixed frequency, there is a current of 0.465 A in the resistor. When only an inductor is connected across the terminals of this same generator, there is a current of 0.360 A in the inductor. When both the resistor and the inductor are connected in series between the terminals of this generator, calculate the following.
(a) the impedance of the series combination


(b) the phase angle between the current and the voltage of the generator"

I got the impedance to be 389.94, but I don't know what other formulas to use to get the phase angle. Specifically, I don't know how to find XL.


Homework Equations



Phase angle = arctan(XL/R)
 
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Nvm, I found another formula for phase angle = cos(R/Z)

I had the wrong variables written into the equation of Z, so I didn't realize I already calculated XL >.<
 
Last edited:
I don't know how to find XL.

How would you find R? It is similar.
 
theintarnets said:
Nvm, I found another formula for phase angle = cos(R/Z) ✗[/size][/color]

phase angle ɸ = cos⁻¹ (R/Z)

this is identical with ɸ = tan⁻¹ (X/R)
 
barryj said:
I don't know how to find XL.

How would you find R? It is similar.
Ohm's Law, you know the applied voltage and you know the current that flows.
 

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