Question

A current of $5\, A$ passes through a copper conductor (resistivity = $1.7 \times 10^{-8} \; \Omega m$) of radius of cross-section $5\, mm$. Find the mobility of the charges if their drift velocity is $1.1 \times 10^{-3}\, m/s$.

• A. $1.3 \; m^2 /Vs$
• B. $1.5 \; m^2 /Vs$
• C. $1.8 \; m^2 /Vs$
• D. $1.0 \; m^2 /Vs$

Answer 1

Answer: (D)

$\mu = \frac{V_{d}}{E} E = \rho J $
$ = \frac{1.1 \times10^{-3}}{1.7 \times10^{-8} \times\frac{5}{\pi \times25\times10^{-6}}} $
$ = \frac{1.1 \times 10^{-3} \times \pi \times 25 \times 10^{-6}}{1.7 \times10^{-8}\times5}\approx1.01m^{2} /Vs$