Resistivity
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- Опубликовано: 16 окт 2024
- This video is about Resistivity, what happens when the cross sectional area of cable changes. What does type of conductor and length do to resistance. This can be applied to fault finding if you know the resistance, conductor type and CSA, then you can find the distance to the fault - just rearrange the formula.
Discover what Rho is and apply to all electrical principles exams great for all level 2 or 3 electrical qualifications.
Infinitefury234 commented: (for some reason I cannot see the comment properly) the answer @7:46 was wrong, the answer is correct, you just need to put x10^9 not x10^1. Hope that helps.
Thanks a lot for this tutorial. Everything makes perfect sense how you described it. However, I got lost with the result of your first calculation. Would you be able at all to let me know in the comments how you ended up with 1.153 as the result? It would've been great if the equation had been broken down into 2 or 3 more steps for clarification. I somehow ended up with 19.95. I wrote out the exponents to their decimal numbers to be able to understand the math path, but it didn't add up for me. Thanks a lot!
I'm glad you have found it useful. I have tried the calculation again trying different permutations where people normally go wrong, but I do not get to your answer. Try looking at my video on Engineering Notations to check your use of the calculator - ruclips.net/video/e4ka9Lvj45U/видео.html
Maybe check you have put brackets in! - This could be required depending on type (Age) of calculator.
Hope this helps - Please Like Share & Subscribe.
Thank you very much , what a video explaining resistivity. Well done 👏
You're welcome, please like share and subscribe. Many thanks.
@@sparkyhelp3997 i have shared your channel with my other colleagues at the college .
@@helim0101 thank you
I don't understand how you got 1.5mmx10 to the power of minus 6. Do you do this for every calculation with this formula?
I do explain it in the video (I think!), but it converts it to square metres to keep all the units the same for the calculation.
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Yes sir, is it micro? or milli , i think milli is 10 ^-3…..?
Ah ok i got it, its mm squared!
hey sparky me again haha,
how would you go about finding the out the length of a cable needed when you have no resistivity.
The question Im trying to answer only gives me the CSA, The conducting material, the voltage it may not exceed which is 11.5 and a amp of 13. I know I have to transpose the resistivity formula giving me L=RA/P but I just dont know how to find out the resistivity in the equation.
Please help
apply ohms law R=Vd/I = 11.5/13 then apply resistivity. Please like and share.
@@sparkyhelp3997 man I really do appreciate this thank you, liked and shared your video already. Thanks again
@@sparkyhelp3997 This is the question Im having trouble answering. "An immersion heater takes a current of 13A and is fed through a twin cable, each core having a CSA of 2.5mm2. If the conductors are made of copper and have a resistivity of 17.2 x 10-9 Ω/m3, calculate the greatest length of cable which may be used, if the cable voltage drop is not to exceed 11.5 volts"
@@MomentsWithBrandon Hi, Again work out the resistance (back to ohm's law) R=V/I = 11.5/13= R. then apply to the resistivity formula to calculate the length (see video on transposition). Good luck.
@@sparkyhelp3997 Thanks boss
How he got his role confuse me can somebody explain please
Rho? - not sure what you are asking?
This 10 to the power of confuses me. Can anyone elaborate on this please?
I'm currently working a quick video to help explain, watch this space. Please Like, Share & Subscribe.
@@sparkyhelp3997 That would be amazing! Thanks! My calculations are coming out right, I just don't get -9 or -6 why not -987?!?!! 🫣 Your examples are helping no end!
According to my textbook you're rho figures are slightly wrong.
According to my textbook:
Copper: 17.5 X 10 ‐⁹
Aluminium: 28.5 X 10‐⁹
Hi,
The Rho for copper used in the video is for annealed copper, what is the value in the text book for?
There will also be different rhos for aluminium depending on its composition. Your text book rho is out by 0.0000000001 from the one used in this video. Always use the Rho for the type of material you are trying to calculate. I would guess that the text book has used different types of alloy of these materials, this would explain their different values. Maybe you should message the author to get them also to clarify their values.
I hope you understood how to do the calculation, because that is the point and the reason why I have put the video together. You can then use any values you wish. Hope that helps.
Thank u!
You're welcome! Please Like, Share & Subscribe.
Sorry sir......... Mili is 10^-3
Hi, thankyou for your comment, you are quite correct milli is to the minus three, however the units have to be all the same e.g, meters, therefore, milli meters has been changed into meters as a number hence to the minus six. I hope that has answered your question.
Why does every single person who makes videos relating to electricity talk so quietly. Its impossible to follow. Theyre all whispering
We are all Electrical and not Sound engineers! Sadly, sound cannot be altered after uploading. I am aware of it, and hopefully all future videos have a higher volume.