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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.
 one year ago
 one year 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.
 one year ago
 one year ago

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ash2326Best ResponseYou've already chosen the best response.3
Copper 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
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
Yeah, now find volume Volume= mass/density
 one year ago

theyatinBest ResponseYou've already chosen the best response.0
density hai mass hai volume= length into cross section you can find length
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
@ash2326 @theyatin what do you think?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
Yeah you're right. Sorry My battery was out of juice
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
than after i got the volume, whats next? getting the length?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
\[\text{Volume}= \text{Area of Cross section} \times \text{length}\]
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
length=volume/ area of cross section?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
Yeah, remember to convert cross section into cm^2, it's given in mm^2 Then you'll get length in cm
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
length= 1,349.83 cm^2/0.209cm^2 ??
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
1 mm = 1/ 10 cm \[1 mm^2= \frac{1}{10\times 10} cm^2\]
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
area of cross section=2.09 mm^2=2.09/100 cm^2
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
yeah now you find length
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
length= 1,349.83 cm^2/0.0209cm^2 ?
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
what would be the unit?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
\[\frac{cm^3}{cm^2}\]???
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
oh i get it. its cm. cause i saw both cm^2
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
good, now you have the length. You need to find the resistance. Do you have any idea, how to find that?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
that'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
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
R=ρ(micro ohmscm)×3090199.522 cm ?
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
then multiply it to 1924 ?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
Yeah this is right but this in micro ohms. Divide by 10^6 to get resistance in ohms
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
why divide it by 10^6 ?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
Because resistance we found is in micro ohms \[1 micro ohm=\frac{1}{10^6} \text{ohms}\]
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
oh okay thanks so the answer will be 5945.54 ohms ?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
Yeah 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
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
so that must be 645.8517 ?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
64585.17/100=>64.581517 meters
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
yeah, you're right. Sorry :(
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
its alright :) then whats next? we will repeat it again? because we got the wrong length?
 one year ago

ash2326Best ResponseYou've already chosen the best response.3
nope, we found the resistance correctly. question asked length in meters that's why we changed it
 one year ago

alfers101Best ResponseYou've already chosen the best response.1
oh thanks a lot. :D a massive thank you! God bless :D
 one year ago
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