# Use a simulator to produce a resonance curve for this RLC circuit

• Comp Sci
• leejohnson222
leejohnson222
Homework Statement
RLC series circuit

Vs (10 +j20) R = 100 Xl = +300 Xc = -j200

use a simulator to produce a resonance curve for the circuit between 800 Hz
and 4.5 kHz.
Relevant Equations
i would convert the given numbers so they can be used in a sim,
so
impedance Z = R + j (lL - Xc)
Xl = 2pifL
Xc = 1/ 2pifC1

Then i think you would need to convert Xl and Xc into L and C using the formulas
L = Xl/ 2pif

C = -1 /2pifXc
my issue here is what would i put in for frequency ? unless i use the formula to find the resonance frequency
i have only used multisim live and you cant put in Vs 10 +j20

leejohnson222 said:
my issue here is what would i put in for frequency ? unless i use the formula to find the resonance frequency
i have only used multisim live and you cant put in Vs 10 +j20
You could pick an arbitrary frequency between the given values, such as the midpoint, 2650 Hz. Then solve for the components from there. You weren't given a specific value of frequency, only a range that (presumably) the resonance would occur in.

As for the voltage source, ##V_s##, that specifies a magnitude and angle (not the frequency!)
So find the magnitude and angle from the given value. You should be able to specify the magnitude and angle in the source voltage in multisim?

ok makes sense to pick the mid point of the frequency for the formulas as this is what the questions wants me to look at. I think the imedance of the circuit is (100 + j100) and i think Current = (0.149 + j0.049)a
so V = I x Z ?

leejohnson222 said:
ok makes sense to pick the mid point of the frequency for the formulas as this is what the questions wants me to look at. I think the imedance of the circuit is (100 + j100) and i think Current = (0.149 + j0.049)a
so V = I x Z ?
You've already got the voltage, no? The current is just ##I = V_s/Z##.

i have the given Voltage but i can see how i can enter that form into multism, it wants voltage and freq
unless im missing some options, i need to do the maths to work out the L and C then draw up the circuit in the sim

leejohnson222 said:
i have the given Voltage but i can see how i can enter that form into multism, it wants voltage and freq
unless im missing some options, i need to do the maths to work out the L and C then draw up the circuit in the sim
In LTSPICE the voltage source gives you the option of SINE and you can specify the AC voltage and Frequency, as well as a value for Phi, the angular offset.

I don't know what Multisim gives (I don't have it installed, or signed up for the online version). But surely there must be some option for specifying the angle of the source? If you can do a screenshot of the options for the source voltage, maybe we can take a look?

Edit: Changed Theta to Phi.

LT spice sounds like a good option, i can not get it to install on my mac

Vs magnatude is this the formula ? Sq root (102 + 202) i think i am getting myself mixed up, multism wont allow me to not enter a frequency for voltage, not sure what to use for that

i think i have made an error here as the question says L = +300 ohms C = -j200ohms
so they are not Xl and Xc

Last edited:
leejohnson222 said:
Vs magnatude is this the formula ? Sq root (102 + 202) i think i am getting myself mixed up, multism wont allow me to not enter a frequency for voltage, not sure what to use for that
For a Bode plot (sweeping through multiple frequencies) you'll want to specify the voltage and frequencies in a different way. There should be some entries equivalent to LTSPICE's 'Small signal AC analysis' in the setup for the voltage source, probably shown as magnitude and phase?

For the bode plot you'll have to work out how Multisim does that. Probably some setting for AC Analysis, as opposed to Transient Analysis. You'll specify the frequency range there I think.
leejohnson222 said:
i think i have made an error here as the question says L = +300 ohms C = -j200ohms
so they are not Xl and Xc
I think that those are impedances (Z), and there's a typo for the inductance: Should be L = +j300 ohms. Inductances have +j impedances and capacitance have -j impedances. They really shouldn't have used L and C for those values, as those symbols represent the real values of inductance and capacitance (henries and farads), not their impedances.

leejohnson222
yes this is where i am getting mixed up as the circuit says L and C but no units for L or C, so as you say they may be impedance rather than henries or farads.
I will get spice running on my computer and see how i get on, thank you

Something is missing from this puzzle, lost in translation.
Is there a link somewhere to the original question or challenge ?

yes here,
use a simulation and produce a resonance curve for the circuit between 800h and 4.5 kHz.

## What is a resonance curve in an RLC circuit?

A resonance curve in an RLC circuit is a graphical representation of the circuit's response, typically the amplitude of the voltage or current, as a function of the frequency of the input signal. It shows how the circuit's impedance varies with frequency and highlights the resonant frequency where the impedance is minimized, and the amplitude is maximized.

## How do I set up a simulator for generating a resonance curve for an RLC circuit?

To set up a simulator for generating a resonance curve, you need to define the circuit components (resistor, inductor, and capacitor) and their values. Then, configure the simulator to sweep the input signal frequency over a desired range. Finally, plot the amplitude of the voltage or current against the frequency to obtain the resonance curve.

## Which parameters of the RLC circuit affect the shape of the resonance curve?

The shape of the resonance curve is influenced by the values of the resistor (R), inductor (L), and capacitor (C). The resonant frequency is determined by the values of L and C, while the bandwidth and peak amplitude are affected by the resistance R. A higher resistance broadens the curve and lowers the peak amplitude, while a lower resistance sharpens the curve and increases the peak amplitude.

## What software tools can be used to simulate an RLC circuit and produce a resonance curve?

Several software tools can be used to simulate an RLC circuit and produce a resonance curve, including LTSpice, Multisim, PSpice, MATLAB, and CircuitLab. These tools allow you to model the circuit, perform frequency sweeps, and visualize the resulting resonance curve.

## How can I interpret the results of the resonance curve for an RLC circuit?

The resonance curve provides insights into the circuit's behavior at different frequencies. The peak of the curve indicates the resonant frequency where the circuit is most responsive. The width of the curve around the peak (bandwidth) indicates how selective the circuit is to a narrow range of frequencies. A narrow bandwidth implies high selectivity, while a wide bandwidth indicates lower selectivity. The quality factor (Q factor) can also be derived from the curve, representing the sharpness of the resonance.

• Engineering and Comp Sci Homework Help
Replies
8
Views
2K
• Engineering and Comp Sci Homework Help
Replies
17
Views
648
• Engineering and Comp Sci Homework Help
Replies
12
Views
2K
• Electrical Engineering
Replies
5
Views
956
• Engineering and Comp Sci Homework Help
Replies
15
Views
2K
• Introductory Physics Homework Help
Replies
12
Views
5K
• Engineering and Comp Sci Homework Help
Replies
6
Views
3K
• Engineering and Comp Sci Homework Help
Replies
2
Views
3K
• Engineering and Comp Sci Homework Help
Replies
6
Views
4K
• Engineering and Comp Sci Homework Help
Replies
16
Views
3K