Question

The drift velocity of electrons in silver wire with cross sectional area $3.14 \times 10^{-6} m ^{2}$ carrying a current of $20 \,A$ is. Given atomic weight of $A g=108$, density of silver = $10.5 \times 10^{3} kg / m ^{3}$.

• A. $2.798 \times 10^{-54} m/ sec $
• B. $67.98 \times 10^{-54} m/ sec $
• C. $0.67 \times 10^{-54} m/ sec $
• D. $6.798 \times 10^{-54} m/ sec $

Answer 1

Answer: (D)

Number of electrons per kg of silver $\frac{6.023 \times 10^{26}}{108}$
Number of electrons per unit volume of silver
$n=\frac{6.023 \times 10^{26}}{108} \times 10.5 \times 10^{3}$
$v_{d}=\frac{I}{n e A}$
$=\frac{20}{6.023 \times 10^{26} \times 10.5 \times 10^{3} \times 1.6 \times 10^{-19} \times 3.14 \times 10^{-6}}$ $\times 108$
$=6.798 \times 10^{-4} m /sec .$