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1)

When 5V  potential difference is applied across a wire of length 0.1m  the drift speed of electrons is  2.5×104ms1. If the electron density in the wire is  8×1028m3  the resistivity of the material is close to Ωm


A) 1.6×108 Om

B) 1.6×107 Om

C) 1.6×106 Om

D) 1.6×105 Om

Answer:

Option D

Explanation:

According to the question

2622021587_m23.PNG

 vd=2.5×104m/s

          n=8×1028/m3  

   we know that     J=nevd   or   I=nevdA

 where,    symbols have their usual  meaning

      VR=nevdA

      or        VρLA=nevdA

     or     VρL=nevd

   or     ρ=VnevdL

      =    58×1028×1.6×1019×2.5×104×0.1

          or    ρ    =1.6×105  Ωm