Calculating inductance of an LR and RLC Circuit?

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Homework Help Overview

The discussion revolves around calculating the inductance in both LR and RLC circuits using a function generator that produces a 1000 Hz square wave. Participants are tasked with determining the inductance values based on given resistances and capacitances, while also exploring how changes in resistance affect inductance.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the lack of clear formulas for calculating inductance in the context of the given circuits. Questions arise regarding the interpretation of the function generator's output and its implications for the calculations. Some participants express uncertainty about which equations to apply for the RLC circuit.

Discussion Status

There is ongoing exploration of the problem, with some participants attempting to derive inductance values while others seek clarification on missing information. Guidance has been offered regarding the interpretation of the function generator's settings and the importance of oscilloscope readings, though no consensus has been reached on the calculations themselves.

Contextual Notes

Participants note that critical information appears to be missing from the original problem statement, particularly regarding the function generator's output and its measurement. There is a suggestion that understanding the waveform at "Ch. 1" is essential for accurately determining inductance.

WK95
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Homework Statement


For both the LR and RLC circuit, a function generator is used to create a 1000 Hz square wwave of maximum amplitude.
1) For the following LR circuit, the resistance is set to a 100 Ohms. Determine the inductance, L. How does the inductance vary if the resistance were increased to 200 Ohms[/B]
5WUQFAq.png

2) For the following RLC circuit, the capacitance is set to a 0.001 micro F. Determine the inductance, L.
SBr0Irn.png

Homework Equations


2) F_0 = 1/ (2*pi* sqrt(LC))
ω^2 = (1/LC)(1 - (C*R^2)/(4L))
ω=2*pi*f


3. The Attempt at a Solution

1) I can't find any formulas for this one.
2) For question 2, I don't know which equation should be used. Also, I assume that f=1000Hz. For the second equation, R is the total circuit resistance, C is the capacitance, and L is the inductance.
 
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I've found an equation for question 1.

V=V_0(e^(-Rt/L))
 
For question 1, I got the inductance to be 0.114 mH.
 
bump
 
WK95 said:
For question 1, I got the inductance to be 0.114 mH.
You did? Without knowing anything about the signal at "Ch. 1"? Wow! Show us how!
 
WK95 said:

Homework Statement


For both the LR and RLC circuit, a function generator is used to create a 1000 Hz square wwave of maximum amplitude.
1) For the following LR circuit, the resistance is set to a 100 Ohms. Determine the inductance, L. How does the inductance vary if the resistance were increased to 200 Ohms[/B]
5WUQFAq.png

2) For the following RLC circuit, the capacitance is set to a 0.001 micro F. Determine the inductance, L.
SBr0Irn.png

Homework Equations


2) F_0 = 1/ (2*pi* sqrt(LC))
ω^2 = (1/LC)(1 - (C*R^2)/(4L))
ω=2*pi*f


3. The Attempt at a Solution

1) I can't find any formulas for this one.
2) For question 2, I don't know which equation should be used. Also, I assume that f=1000Hz. For the second equation, R is the total circuit resistance, C is the capacitance, and L is the inductance.
Please give the problem statement as it was given to you. It clear that some critical information is missing.

What does it mean for the function generator to produce a wave of maximum amplitude?

Is it perhaps the wave at Ch. 1 which has to have maximum amplitude?
 
SammyS said:
Please give the problem statement as it was given to you. It clear that some critical information is missing.

What does it mean for the function generator to produce a wave of maximum amplitude?

Is it perhaps the wave at Ch. 1 which has to have maximum amplitude?
Yes, my apologies. I've neglected to include the relevant oscilloscope readout.
zYefk3g.jpg

Vertical Scale: 100mV/DIV
Horizontal Scale: 50 microsecond/DIV

gfg8210-600.jpg

Here is a the function generator used. Notice the AMPL knob to the right. Maximum amplitude means turning it all the way counterclockwise.
 
rude man said:
You did? Without knowing anything about the signal at "Ch. 1"? Wow! Show us how!
Simple. Since I didn't know anything about what was in Ch. 1, I simply had to find it out. You can as well if you were to make the circuit as shown in the initial post.
 
WK95 said:
Simple. Since I didn't know anything about what was in Ch. 1, I simply had to find it out. You can as well if you were to make the circuit as shown in the initial post.
Yeh, but you didn't know L either. You were supposed to find L given Ch. 1.
I see you did post the Ch 1 waveform later. Much better.
It would further be helpful if you provided us with the amplitude of the square-wave generator, although one can estimate L based on the decay profile in Ch. 1.
 

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