Question

If resistivity of copper is $1.72 \times 10^{-8} \Omega$-m and number of free electrons in copper is $8.5 \times 10^{28} / m ^{3}$. Find mobility.

• A. $4.25 \times 10^{-3} m ^{2} / C \Omega$
• B. $6.8 \times 10^{-3} m ^{2} / C \Omega$
• C. $8.5 \times 10^{-3} m ^{2} / C \Omega$
• D. $3.4 \times 10^{-3} m ^{2} / C \Omega$

Answer 1

Answer: (A)

Given,
Resistivity of Copper = 1.72 $\times$ 10^-8 $\Omega$-m
Number of free electrons, n = 8.5 $\times$ 10²⁸ /m3
Mobility, $\mu = \frac{1}{\rho ne}$
$=\frac{1}{1.72\times10^{-8}\Omega m\times8.5\times10^{28}/m^{3}\times1.6\times10^{-19}}$
$=4.25\times10^{-3}m^{2}/C\Omega$