A copper wire has diameter 0.5mm and resistivity of 1.6 x 10 to the power of -8 Ohm m.What will be the length if resistance is 10 Ohm ?

Asked by Faizaan Md | 14th Sep, 2010, 05:23: PM

Expert Answer:

R = p l / A
 
where R = resitance in ohms     = 10 ohm
         p = resistivity in Ohm-m  = 1.6 x 10-8 ohm-m
         l = length in m
         A = cross sectional area in m2 = 3.14 x d2 / 4 = 3.14 x (0.5 x 10-3)2 / 4
                                                                          =  0.196 x 10-6 m2
 
therefore l = RA/p = 10 x 0.196 x 10-6 / 1.6 x 10-8
  =  0.1226 x 103 m
                          = 122.6 m

Answered by  | 14th Sep, 2010, 06:37: PM

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