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alfers101
 3 years ago
This is a problem that i want to solve but i can't really answer it. It's a sample problem from my book:
The density of a copper is 8.89 is 8.89 g/cm^3 and the ρ=1924μΩcm. Determine the length(m) and resistance of 12kg of copper; the crosssection of which in 2.09mm^2.
alfers101
 3 years ago
This is a problem that i want to solve but i can't really answer it. It's a sample problem from my book: The density of a copper is 8.89 is 8.89 g/cm^3 and the ρ=1924μΩcm. Determine the length(m) and resistance of 12kg of copper; the crosssection of which in 2.09mm^2.

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ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Copper wire can be considered as a cylinder. Here we have cross section given as 2.09 mm^2 To find length, we need to find the volume We have the density as 8.89 g/ cm^2 Mass= 12 kg Could you find the volume? Do remember to change mass in kg to grams, this will give you volume in cm^3

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Yeah, now find volume Volume= mass/density

theyatin
 3 years ago
Best ResponseYou've already chosen the best response.0density hai mass hai volume= length into cross section you can find length

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1@ash2326 @theyatin what do you think?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Yeah you're right. Sorry My battery was out of juice

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1than after i got the volume, whats next? getting the length?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3\[\text{Volume}= \text{Area of Cross section} \times \text{length}\]

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1length=volume/ area of cross section?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Yeah, remember to convert cross section into cm^2, it's given in mm^2 Then you'll get length in cm

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1length= 1,349.83 cm^2/0.209cm^2 ??

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.31 mm = 1/ 10 cm \[1 mm^2= \frac{1}{10\times 10} cm^2\]

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3area of cross section=2.09 mm^2=2.09/100 cm^2

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3yeah now you find length

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1length= 1,349.83 cm^2/0.0209cm^2 ?

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1what would be the unit?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3\[\frac{cm^3}{cm^2}\]???

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1oh i get it. its cm. cause i saw both cm^2

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3good, now you have the length. You need to find the resistance. Do you have any idea, how to find that?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3that's right but there is one more relation relating resistance with the property of material and the dimensions of the wire. \[R=\rho(\text{micro ohmscm}) \times \frac{\text{Length (in cm)}}{\text{Area of cross section(in cm^2)}}\] From this you'll get resistance in micro ohms

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1R=ρ(micro ohmscm)×3090199.522 cm ?

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1then multiply it to 1924 ?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Yeah this is right but this in micro ohms. Divide by 10^6 to get resistance in ohms

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1why divide it by 10^6 ?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Because resistance we found is in micro ohms \[1 micro ohm=\frac{1}{10^6} \text{ohms}\]

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1oh okay thanks so the answer will be 5945.54 ohms ?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3Yeah that's all we found length and resistance Wait a min, we need to find length in meters. For that divide length in cm by 100 as 1 meter= 100 cms

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1so that must be 645.8517 ?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.364585.17/100=>64.581517 meters

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3yeah, you're right. Sorry :(

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1its alright :) then whats next? we will repeat it again? because we got the wrong length?

ash2326
 3 years ago
Best ResponseYou've already chosen the best response.3nope, we found the resistance correctly. question asked length in meters that's why we changed it

alfers101
 3 years ago
Best ResponseYou've already chosen the best response.1oh thanks a lot. :D a massive thank you! God bless :D
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