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16-Pearl
September 8, 2022
Question

Mathcad Community Challenge September 2022 - Resistors in Parallel

  • September 8, 2022
  • 14 replies
  • 19244 views

This month’s challenge is related to electrical engineering. We have a simple circuit with an electrical potential of 220 Volts. Initially we have a single 10 Ohm resistor. Then we add a second resistor in parallel, with 10% higher resistance. Then we add a third resistor in parallel, with 10% higher resistance than the previous resistor. And so on.

  • Calculate the current in the circuit for the single resistor case.
  • Calculate the resistance of each additional resistor and current through each resistor for 2, 3, 4, 5, and 10 resistors in parallel.
  • Can you write a function or program that calculates the resistance of each resistor and current through each resistor for n resistors in parallel?

These calculations are fairly straightforward, so it will be interesting to see what tools – vectors, matrices, loops, plots, charts, etc. – that you use to solve the problem. As always, how you document your calculations is important as your worksheet will be visible to the community.

Here is an example of three resistors in parallel, as drawn in Creo Schematics:

Resistors Challenge.png

Find the Mathcad Community Challenge Guidelines here!

14 replies

12-Amethyst
September 19, 2022

Strib_11-1663558647692.png

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12-Amethyst
September 19, 2022

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18-Opal
September 19, 2022

Please attach the file. 

23-Emerald I
September 24, 2022

Very nice calculation!  Well done!

 

Not criticisms, just comments:

       1)    Not sure why you changed the default ORIGIN.  If that's your default choice, okay; but understanding somebody else's sheet may be confusing,

      2)  (And, IMHO opinion, more important)  Don't divide out units in functions unless you absolutely must!  Your equation for total resistance stripped the units.  (I know why,)  But you didn't need to, and the equivalent equation is simpler and  easy to visualize:

Fred_Kohlhepp_0-1664020708010.png

Welcome to Mathcad!

 

4-Participant
September 29, 2022

Fred:

Thanks for the comments.... I should have simplified the equation a bit!

 

With regards to the ORIGIN change... the thought was that I wanted there to be no R0... R1 was to be the first resistor.  In playing around with the code though, it appears it works a bit differently that I had understood. Working on that...

 

thanks


Adam 

1-Visitor
September 27, 2022

Opting to make a work sheet that uses "for" loops,  is easy for a student to follow, and is scalable.

18-Opal
September 29, 2022

I hope Dave can handle going through the volume of people getting into the challenge this time! I'm looking forward to what he has to say about the contributions.

 

September ends after tomorrow, so if you're still thinking about submitting something, now's the time!

16-Pearl
September 29, 2022

Ha ha, I was thinking about that myself. I had no idea this challenge would be so popular. I've got my work cut out for me this weekend. I'll be reviewing all submissions while watching football. Speaking of which, I have an idea for a football-related geometry problem for November. So football fans, stay tuned...

12-Amethyst
September 29, 2022

Hi Dave,

Yes, you generated a lot of interesting responses!

I hope you like my simple closed-form expression for the solution – that didn’t even use Mathcad. No offense intended in doing that – have used MCD for EE work since its DOS version.

Strib