# physics

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An iron wire has a cross-sectional area equal to 1.20 10-5 m2. Carry out the following steps to determine the drift speed of the conduction electrons in the wire if it carries a current of 34.0 A.
(a) How many kilograms are there in 1.00 mole of iron?
1 kg/mol

(b) Starting with the density of iron and the result of part (a), compute the molar density of iron (the number of moles of iron per cubic meter).
2 mol/m3

(c) Calculate the number density of iron atoms using Avogadro's number.
3 atoms/m3

(d) Obtain the number density of conduction electrons given that there are two conduction electrons per iron atom.
4 electrons/m3

(e) Calculate the drift speed of conduction electrons in this wire.
5 m/s

• physics -

They are trying to take you through the steps of computing the drift speed of elctrons in a wire. You should make an effort to follow the steps.
(a) The atomic weight of iron is 55.9, so there are that many grams per mole. How many kg is that? 5.59*10^-2 kg/mol
(b) They expect you to look up the density of iron and use that and the part (a) answer to compute the number of moles per m^3.

___kg/m^3/5.59*10^-2 kg/mole = ___ mole/m^3
(c) Multiplying by Avogadro's number will give you the number of Fe atoms per m^3.

(d) Multiply that by 2 for the free electron number desnity, Ne

(e) Ne*drift speed*(wire area)*e = 34 Coulombs/s
(e is the elctron charge)
Solve for the electron drift speed. it will be rather slow

Fill in the blanks.

• physics -

221.224

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