Multisim rms current and voltage RLC Circuit

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Discussion Overview

The discussion revolves around calculating the rms current and voltage in an RLC circuit at resonance using Multisim. Participants share their calculations, seek validation, and discuss issues related to simulating the circuit in the software.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents component values (R = 500 ohm, L = 0.40 mH, C = 100 pF) and claims to have calculated the rms current (0.002 A) and voltages across each element at resonance.
  • Another participant questions the calculated resonant frequency, suggesting it seems small given the component values.
  • A later reply provides a detailed calculation of the resonant frequency (795.77 kHz) and the inductive and capacitive reactance at resonance, along with the impedance and rms current and voltages across the elements.
  • Some participants express that the calculations appear improved but still struggle to replicate the results in Multisim.
  • One participant notes the potential issue of having multiple multimeters in the circuit and suggests simplifying the setup for accurate measurements.

Areas of Agreement / Disagreement

Participants generally agree on the calculations presented, but there is disagreement regarding the initial resonant frequency and the effectiveness of the Multisim setup. The discussion remains unresolved regarding the correct implementation in Multisim.

Contextual Notes

Participants express uncertainty about the accuracy of their Multisim setup and the implications of their circuit configuration on the measurements. There are unresolved questions about the appropriateness of the component values and their impact on the resonant frequency.

k31453
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Trying to find rms current at resonance and rms voltage across each elements (resistor, inductor and capacitor)

I got the answers but i want it do in multisim !

i got :

R = 500 ohm
L = 0.40mH
C = 100pF

The answer is

rms current: 0.002A
rms voltage:
Vr = 1V
Vc = 126.52 V
Vl = 126.52 V

The resonant freq. is 25.16 Khz at 1v RMS ac source.


this is my attempt !

Homework Statement


Homework Equations


The Attempt at a Solution

 
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How did you arrive at the resonant frequency? It looks a bit small to me, given the stated component values.
 
gneill said:
How did you arrive at the resonant frequency? It looks a bit small to me, given the stated component values.


sorry this is the answers

A) resonant frequency
ans: f = 1/2*pi*sqrt(LC)
= 1/(2*pi*sqrt(0.0004 * 100 * 10^-12)
= 795.77 Khz

b) the inductive and capacitive reactance at resonance
ans: XL = 2*pi*f*L
= 2*pi* 795.775*10^3*0.0004
= 2000 ohm

Xc = 1/(2*pi*f*C)
= 1/(2*pi* 795.775*10^3 * 100 * 10^-12)
= 1999.9998 ohm

C) the impedance at resonance

ans : impedence of resonance is resistance of circuit : z = R = 500 ohm

D) the rms current at resonance
ans: I = V/R = 1/500 = 0.002A

E) the rms voltage across each element at resonance
Ans: Vr = IR
= 0.002 * 500
= 1V

VL = IXL
= 0.002 * 2000
= 4V

Vc = IXc
= 0.002 * 1999.99
= 3.99998 V
 
Yes, that looks better.
 
gneill said:
Yes, that looks better.

but still i can't prove into multisim !
 
k31453 said:
but still i can't prove into multisim !

I don't have Multisim, so I can't help with the details of using it. Sorry.

But looking at the image you've provided, I would say that there sure are a lot of multimeters inserted, presumably to measure current. Surely one would suffice for a series circuit? Also, it appears that the inductor's top end is open circuited and it is being bypassed by a multipmeter (to measure voltage?). I'd suggest removing all but one multimeter to measure the series current, and make sure that the circuit is unbroken and operational before adding multimeters in parallel with the components to measure their voltages.
 

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