Trying to find either of the two unknowns which is either Impedance or Resistance.

Thread Starter

riz-1

Joined Dec 29, 2019
4
Hello I am currently preparing for my final exams for sixth form in a UTC, which has 4 exam papers in January, they are Mathematics for Engineering, Science for Engineering, Principles of Mechanical for Engineering and Electrical and Electronic principles for Engineering.

I am comfortable with Mathematics, Science and Mechanical, however I struggle on the Electrical unit. I also take an A-level course on Mathematics

I am using revision material called Skeleton notes and I am struggling on a certain part on the Electronics side. Here is the link (Page 7): Link

So it's going to be this part https://ibb.co/s2skJXp (3rd last row where I have already found Inductance but not Resistance and Impedance) I have to find either the Impedance or the Resistance using the formulas below:

These are the formulas that we're supposed to use:

Formula that I wrote down on my Pukka pad

The section I got the formula from

Source for the 3 formulas (Page 15)

These are the answers for that question but I don't know how they got them. Link

I attempted this myself when I tried re-arranging the formula, or subbing it and re-arranging it but to no avail have I got the solution. It left me with either a math error or a higher value than the answer.

Calculator I use: CASIO fx-991EX CLASSWIZ (My calculator is in degrees and in calculate mode, I did not change the settings.)


Any help is greatly appreciated.
 

MrAl

Joined Jun 17, 2014
6,945
Hi,

Your notes are hard to read so let's take one at a time.

The first row reads:
1k, 1mH, reactance?, impedance?, phaseangle?

You have formulas for all three, so were you able to solve for those three unknowns?
 

Thread Starter

riz-1

Joined Dec 29, 2019
4
Hi,

Your notes are hard to read so let's take one at a time.

The first row reads:
1k, 1mH, reactance?, impedance?, phaseangle?

You have formulas for all three, so were you able to solve for those three unknowns?
Thank you for your reply MrAl,

Sorry I didn't explain myself well on the row i'm struggling on.

I have attached a pdf file to elaborate on what I need help with.
Attached below,
 

Attachments

Thread Starter

riz-1

Joined Dec 29, 2019
4
So I did a similar question with the same situation for Capacitance and got it right, as the formula to find Impedance when you have no Resistance would be Z²=Xℂ²∕Sin²θ (Where C is the sub-script) and this would also work for XL (Where L is the sub-script) they're basically the same formula but different letter types. I hope that the person who created the skeleton note answers made a mistake with their calculations which misleads us as a result. I now feel a bit more confident with this practice of doing the calculations I look forward to coming back to "allaboutcircuits" soon. See you all later.
 
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