What will be the voltage across the resistor in an AC circuit?

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SUMMARY

The discussion centers on calculating the voltage across a resistor in an AC circuit consisting of a 250 ohm resistor, a 1.2 mH inductor, and a 1.8 µF capacitor connected in series to a 120 V, 60 Hz peak source. The initial calculation using the peak current formula (I_peak = V_app peak / Z) yielded a voltage of 20.1 V across the resistor. However, the correct voltage is 14 V, which accounts for the root mean square (RMS) voltage measurement typically used in practical applications.

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  • Understanding of AC circuit components: resistors, inductors, and capacitors
  • Familiarity with impedance (Z) calculations in AC circuits
  • Knowledge of peak and RMS voltage concepts
  • Ability to apply Ohm's Law in AC circuits
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  • Research how to calculate impedance in RLC circuits
  • Learn about the differences between peak voltage and RMS voltage
  • Study the application of voltage meters in AC circuits
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Electrical engineering students, hobbyists working with AC circuits, and professionals involved in circuit design and analysis will benefit from this discussion.

jaejoon89
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Homework Statement


Connecting a 250 ohm resistor, 1.2 mH inductor, and 1.8 micro F capacitor in series across a 120 V, 60 Hz peak source, what will the voltage be for the resistor?

Homework Equations



1) I_peak = V_app peak / Z
2) V_R = I_peak * R

?

The Attempt at a Solution


I used equation 1) to get I_peak, and then equation 2) to get V_R which I calculated at 20.1 V. The answer's 14 V and I don't understand how the book is getting this
 
Last edited:
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Hi jaejoon89,

jaejoon89 said:

Homework Statement


Connecting a 250 ohm resistor, 1.2 mH inductor, and 1.8 micro F capacitor in series across a 60 Hz, 120 V peak source, what will the voltage be for the resistor?


Homework Equations



1) I_peak = V_app peak / Z
2) V_R = I_peak * R

?

The Attempt at a Solution


I used equation 1) to get I_peak, and then equation 2) to get V_R which I calculated at 20.1 V. The answer's 14 V and I don't understand how the book is getting this

Were they asking for the peak voltage or the rms voltage across the resistor?
 
Ah ha! I get it now, they want the rms since it's being read by a voltage meter. Thanks!
 

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