Why Does My Inductive Impedance Calculation Seem Incorrect?

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Discussion Overview

The discussion revolves around the calculation of inductive impedance and the overall impedance in RLC circuits. Participants are exploring the mathematical approach to these calculations, particularly focusing on the values used and the implications of frequency on reactance. The scope includes technical reasoning and potential errors in calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents calculations for inductive impedance and expresses confusion about the results, questioning the validity of their approach.
  • Another participant suggests that the low frequency used (10Hz) may lead to minimal effects from reactive elements, implying that higher frequencies could yield different results.
  • A participant expresses uncertainty about their mathematical skills and the significance of digits in their calculations, indicating a lack of confidence in their results.
  • There is a repeated concern about discrepancies between personal calculations and results from online calculators.
  • One participant reminds another to ensure they take the square root of their final impedance calculation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the calculations or the reasons for discrepancies. Multiple views on the impact of frequency and the interpretation of significant digits remain unresolved.

Contextual Notes

Participants mention the importance of significant digits and the potential influence of frequency on reactance, but these concepts are not fully explored or agreed upon in the discussion.

thepipersson80
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Hi guys,

Firstly I apologise that I'm even asking this... I have gone over it so many times now I don't know what to believe is the right answer, can someone please help me out and let me know where I'm going wrong PLEASE

Ok so first is the inductive impedance

Z= SQRT R^2 + (WL)^2

R = 2.7*10^6 2.7MΩ
W= 2piF = 2pi*10 2pi*10Hz
L= 300*10^-3 300mH

R^2 = 7.29*10^12
WL = 18.84955592 WL^2 = 355.3057584
R^2+WL^2 = 7.29*10^12 + 355.3057584 =7.29*10^12

How can that be right? I may of well just squared R to start with... so what am I doing wrong?

Second,

Impedance in RLC circuits

Z= SQRT R^2 +(Xl - Xc)2

W = 2piF = 628318.5307

F = 100*10^3 = 100000
C = 300*10^-6 = 3*10^-4
L = 300*10^-3 = 0.3
R = 2.7*10^6 = 2700000
Xl = WL = 188495.5592
Xc = 1/WC = 5.30516477*10-3

so R^2 +(Xl - XC)^2 = 7.325530574*10^12 and to me that just does not seem the right answer??

Can you guys see where I would be going wrong? and if so how do I put it into my calculator?
Many thanks
 
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Why do you think you are doing something wrong? The reactance factors are frequency dependent. What you have learned is that at 10Hz (a very low frequency) the reactive elements have very little effect. Try higher frequencies.

Side note. Do NOT copy every digit off of your calculator display. It would do you much good to find a explanation of significant digits. This bit of work will save you time and effort in the future.
 
I just don't think it's right? and when I go to a online calculator I get different answers.

My maths is not that great to say the least, so to be honest I don't know what is significant and what isn't (sorry)
 
thepipersson80 said:
I just don't think it's right? and when I go to a online calculator I get different answers.

My maths is not that great to say the least, so to be honest I don't know what is significant and what isn't (sorry)
Don't forget to take the square root, to end up with Z.
 

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