Question

If the resistivity of copper is $1.7\times {10}^{-6}\Omega cm$, then the mobility of electrons in copper, if each atom of copper contributes one free electron for conduction, is
[The atomic weight of copper is $63.54$ and its density is $8.96g/cc$]

• A. $23.36c{m}^2/Vs$
• B. $503.03c{m}^2/Vs$
• C. $43.25c{m}^2/Vs$
• D. $88.0c{m}^2/Vs$

Answer 1

Answer: (C)

$43.25c{m}^2/Vs$

Take a copper wire with $1cc$ volume.
Weight $=8.96g$
No. of atoms = $\frac{8.96}{63.5}\times N_0=0.8497\times {10}^{23}$
No. of electrons = $0.8497\times {10}^{23}$
Conductivity = 1/resistivity = $n\times e\times m$.
$n=$ no. of electrons
$e=$electronic charge.
$m=$ mobility of electrons.
$\frac{{10}^6}{1.7}=0.8497\times {10}^{23}\times 1.6\times {10}^{-19}\times m$
$m=43.25c{m}^2/Vs$