Find power of resistor and source in AC circuit

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SUMMARY

The discussion focuses on calculating the root mean square voltage (Vrms), source current (IS RMS), power factor, and source voltage magnitude (VS) in an AC circuit with a 20Ω resistor dissipating an average power of 500W. The calculations yield Vrms of 100V, IS RMS of 7.05A at an angle of 135 degrees, and a power factor of 0.707. The magnitude of the source voltage (VS) is determined to be 141.4V, represented as -141.4j in complex form. The analysis is based on the equations provided and circuit analysis techniques.

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Homework Statement


If an average power of 500W is dissipated in the 20Ω resistor, find Vrms, I S RMS, the power factor seen by the source, and the magnitude of VS
(Based on circuit in attached diagram)

Homework Equations



Pave= Irms*Vrms*pf*\frac{1}{2}
Imaginary number referred to as "j", not "i".

The Attempt at a Solution


VA=V
By a node equation at node A, we see that \frac{V}{20}= \frac{V<sub>S</sub>}{-j*20}, so V = VS \angle-90

Loop 1: (j*20-j*20)IS -j*20I= VS
By observation, I=V/20, so V=VS\angle90.
Loop 2: (20+j*20)I-j*20IS=0, so IS= 1.41\angle135 *I
= 1.41\angle135 *\frac{V}{20}= 0.0705 V \angle135

Since I and V are in phase, the power across the resistor is 1
Solve for V:
500=V*\frac{V}{20}\frac{1}{2}, so V=\sqrt{20,000}=
100\sqrt{2}=141.4.

Vrms=\frac{V}{\sqrt{2}} =100,

Since V = 100\sqrt{2} IS =7.05 *\sqrt{2} \angle135, so I S RMS = 7.05

V=VS\angle90, so VS=V\angle-90
And IS= 0.0705 V \angle135,
So power factor pf = cos(135-90)= 0.707

VS=V\angle-90 = -141.4*j, so magnitude given by 141.4.

I think I got this right, but I just want to make sure.
 

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Just realized the diagram I attached was small, hopefully this one's easier to read.
 

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  • Circuit drawing.jpg
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Same-same said:

Homework Statement


If an average power of 500W is dissipated in the 20Ω resistor, find Vrms, I S RMS, the power factor seen by the source, and the magnitude of VS
(Based on circuit in attached diagram)

Homework Equations



Pave= Irms*Vrms*pf*\frac{1}{2}
.
Bad start.
 

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