The copper wire whose masses are 8gram and 12gram have length of ratio 3:4.Find the ratio of the resistance.

Asked by Praveen Kumar | 11th May, 2013, 02:19: PM

Expert Answer:

Mass = Density x Volume = Density x Area x Length
 
Since density for copper in both the two wires will be same.
 
So, M1 / M2 = A1 xL1 / A2 xL2
 
or, 8/12 = A1 x3L / A2 x4L
 
So, A1 / A2 = 8/9
 
Hence ratio of resistances = R1/R2
Now R = ?L/A, where Rho is resistivity that is constant for a particular material.
 
So, R1/R2= (L1 / L2) x (A2 /A1) = 3x9/4x8 = 27/32
 

Answered by  | 11th May, 2013, 04:42: PM

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