Copper has one conduction electron per atom.Its density is 8.89 g/cc 4 its atomic mass is 63.54g/mol. If a Cu wire of diameter of 1nm carries a current of 2 A, what is the drift speed of electron in wire ?

Dear Mainak ,

You Can use simple equation :

         I = neAv_d   where n = no of conduction electrons /volume

                                       e = 1.6 x 10^-19 c

                                       A = Area of Cross section of the wire

                                       v_d = Drift velocity

calculation of n

  let us consider a seciton of length  1 m  , volume of that section  =  ∏ r² l    = 7.85 *10^-19  m³

         Mass of piece = ∏ r² l * density  =  6.98  *10^-12  g

    therefore no of moles in that amount  =  6.98  *10^-12  g / 63.54 g  = 1.098 *10^-13 

  no of atoms of copper in this amount  =  1.098 *10^-13 * 6.022 *10^{23  =} 6.617 * 10¹⁰  atoms  =  6.617 * 10¹⁰ electrons

there fore  , n  = 6.617 * 10¹⁰ electrons / 7.85 *10^-19  m³ =  8.43  * 10²⁸

now apply equations ,        2 = 8.43  * 10²⁸ *1.6 *10^-19 * 7.85 *10^-19 *v_d

                                            v_d = 1.88 * 10⁸  m/s 

the value comes out to be too high because the wire is of nano scale, it is still impossible to buildsuch wires.

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