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alfers101
Group Title
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.
 2 years ago
 2 years ago
alfers101 Group Title
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.
 2 years ago
 2 years ago

This Question is Closed

ash2326 Group TitleBest 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
 2 years ago

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
so 12000 g?
 2 years ago

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

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

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
1,349.83 cm^2 ?
 2 years ago

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

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

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

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

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

ash2326 Group TitleBest 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
 2 years ago

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

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

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
.209 cm^2 ?
 2 years ago

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

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
so 0.0209 cm^2 ?
 2 years ago

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

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

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
64,585.17 ?
 2 years ago

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
what would be the unit?
 2 years ago

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

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

ash2326 Group TitleBest 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?
 2 years ago

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
resistance? R=v/i ?
 2 years ago

ash2326 Group TitleBest 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
 2 years ago

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

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
then multiply it to 1924 ?
 2 years ago

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
5945643879 ?
 2 years ago

ash2326 Group TitleBest 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
 2 years ago

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

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

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

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
then whats next? ;D
 2 years ago

ash2326 Group TitleBest 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
 2 years ago

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
so that must be 645.8517 ?
 2 years ago

ash2326 Group TitleBest ResponseYou've already chosen the best response.3
64585.17/100=>64.581517 meters
 2 years ago

alfers101 Group TitleBest ResponseYou've already chosen the best response.1
no its 645.8517
 2 years ago

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

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

ash2326 Group TitleBest 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
 2 years ago

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