What Is the Frequency of the Voltage Source in an LRC Series AC Circuit?

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Homework Help Overview

The discussion revolves around determining the frequency of an AC voltage source in an LRC series circuit, specifically involving a capacitor and a resistor. The original poster presents measurements of voltages across the components and attempts to calculate the impedance.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the impedance using the relationship between voltage, current, and resistance but questions their current calculation of current through the resistor. Other participants question the setup by noting that the circuit is an RC circuit without an inductor, which may affect the calculations.

Discussion Status

Participants are actively engaging with the original poster's calculations, providing feedback on the current and impedance values. There is a mix of interpretations regarding the circuit's nature, and some guidance is offered on recalculating the impedance based on corrected current values.

Contextual Notes

There is a noted confusion regarding the circuit components, specifically the absence of an inductor, which may impact the calculations and assumptions made by the original poster. The original poster's calculations also appear to contain a significant error in the current value, which is being addressed by other participants.

Fisicks
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Homework Statement


An ac voltage source is connected in series with a 1 uF capacitor and a 750 ohm resistor. The amplitude of the voltage source is measured to be 4V rms while the voltages across the resistor and across the capacitor are 3V rms and 2.7V rms respectively. Determine the frequency of the voltage source.


Homework Equations





The Attempt at a Solution

I said that the current going through the resistor is 250, and then Z=(750^2 + (1/wC)^2)^1/2. So i let 4/250=Z but this isn't right, where am i going wrong?

Thanks guys
 
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This is just an RC circuit (no inductor). Anyway, one the problems I can see with your calculations is that if

VR = IZR = IR,

Then I = VR/R = 3 Vrms / 750 ohm = 4 mArms

not 250 A.
 
Ok, so I would do 4/(4x10^-3)=Z then?
 
Fisicks said:
Ok, so I would do 4/(4x10^-3)=Z then?

It should work. Did you try it? Based on your first post, it seems like you know what the correct answer is supposed to be.
 

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