The problem says: An Aluminum wire carrying a current of 5.0Ahas a cross-section

Question

The problem says: An Aluminum wire carrying a current of 5.0Ahas a cross-sectional area of 4.0 x 10^-6 m2. Find the drift speedof the electrons in the wire. The density of aluminum is 2.7 g/cm3.(Assume 3 electrons are supplied by atom).
My question is: after we get the number of atoms of aluminum,do we multiply it by 3 to get the umber the number electrons??since the question is talking about the movement of electrons??,The solution on cramster ignores the number of electrons and plugsin the number of aluminum atoms directly in the final equation. I appreciate ur help.
My question is: after we get the number of atoms of aluminum,do we multiply it by 3 to get the umber the number electrons??since the question is talking about the movement of electrons??,The solution on cramster ignores the number of electrons and plugsin the number of aluminum atoms directly in the final equation. I appreciate ur help.

Explanation / Answer

as we known: I=n*v*|e|*area; v is drif velocity of electron n is concentration of electron if 3 electrons are supplied by atom the number of atom per cubic meter: N=Na*2.7/26.98*106 ; 2.7g/cm3 isdensity , 26.98 is molecular mass => n=N*3=1.81*1029 electrons/m3 =>v=4.32*10-5 m/s =>v=4.32*10-5 m/s

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